Semiconductor device and method of manufacturing the same

ABSTRACT

Insulating films  34  through  38  (of which insulating films  34, 36, 38  are silicon nitride films and insulating films  35, 38  are silicon oxide films) are sequentially formed on the wires  33  of the fourth wiring layer and groove pattern  40  is transferred into the insulating film  38  by means of photolithography. An anti-reflection film  41  is formed to fill the grooves  40  of the insulating film  38  and then a resist film  42  carrying a hole pattern  43  is formed. The films are subjected to an etching operation in the presence of the resist film  42  to transfer the hole pattern into the insulating films  38, 37, 36  and part of the insulating film  35 . Subsequently, the resist film  42  and the anti-reflection film  41  are removed and the groove pattern  40  and the hole pattern  43  are transferred respectively into the insulating film  37  and the insulating film  35  by using the insulating film  38  as mask.

I—This application is a Divisional application of Ser. No. 10/046,814,filed Jan. 17, 2002, now U.S. Pat. No. 6,555,464 which is a Divisionalapplication of application Ser. No. 09/998,649, filed Dec. 3, 2001, nowU.S. Pat. No. 6,528,400 and is a Divisional application of applicationSer. No. 09/637,593, filed Aug. 15, 2000, abandoned each of which is aDivisional application of application Ser. No. 09/585,629, filed Jun. 2,2000, U.S. Pat. No. 6,340,632 the contents of which are incorporatedherein by reference in their entirety.

TECHNICAL FIELD OF THE INVENTION

This invention relates to a semiconductor device and a method ofmanufacturing the same. More particularly, the present invention relatesto a multilayer wiring structure formed by using a so-called damasceneprocess and also to a technology that can effectively be applied to asemiconductor having such a multilayer wiring structure.

BACKGROUND OF THE INVENTION

In the current trend toward high performance micro-semiconductordevices, the multilayer wiring technology is indispensable formanufacturing such semiconductor devices. There is a well knowntechnique of forming a wiring layer in a semiconductor integratedcircuit by forming a thin film of a high melting point metal such as analuminum (Al) alloy or tungsten (w) on an insulating film, subsequentlyforming on the thin film a resist pattern having a profile same as thewiring pattern to be produced there from the metal thin film byphotolithography and then dry etching the thin film, using the resistpattern as mask. However, the technique of using an Al alloy or someother metal material has a major drawback that the wiring resistancerises remarkably to consequently increase the wiring delay and degradethe performance of the semiconductor device as the wiring is down-sized.Particularly, in the case of high performance logic LSIs, the drawbackcan severely damage the performance thereof.

As an attempt for bypassing this problem, there has been proposed aprocess of burying a wiring metal material containing copper (Cu) asprincipal conductor in the grooves formed on an insulating film andsubsequently removing the unnecessary metal outside the grooves by meansof a CMP (chemical mechanical polishing) technique to produce a wiringpattern in the grooves (so-called damascene process).

SUMMARY OF THE INVENTION

However, as a result of research efforts, the inventors of the presentinvention came to find that the damascene process, more particularly thedual-damascene process (for producing both the wiring and the interlayerconnection wiring of a semiconductor device simultaneously after formingwiring grooves for wiring and contact holes for interlayer connections)is accompanied by a problem as described below that has not hithertobeen known.

Firstly, either of two methods may be employed for forming groves(wiring grooves) and holes (connection holes) in the dual-damasceneprocess; a hole-first method and a self-aligning method.

With the hole-first method, deep holes are firstly formed through aninterlayer insulating film (which may be an inter-wire insulating filmto be used for wiring) that is formed on a lower wiring layer until theyget to the latter. To do this, a photoresist film patterned to show somay openings is formed on the interlayer insulating film and then theinterlayer insulating film is dry etched by using the photoresistpattern as mask. Subsequently, the holes are filled with ananti-reflection material or resist and then wiring grooves are formed inthe interlayer insulating film. To form wiring grooves, a photoresistfilm having opening for the grooves is formed on the interlayerinsulating film and then the interlayer insulating film is dry etchedusing the photoresist pattern as mask. The holes are filled with the ananti-reflection material before forming the wiring grooves as describedabove in order to make the photoresist film for forming the wiringgrooves to be accurately exposed to light and improve the processingaccuracy. In other words, unless the holes are not filled with ananti-reflection material, the surface of the photoresist film reflectsthe profiles of the holes in the corresponding areas during the exposureoperation to come to show undulations and no satisfactory surfaceflatness can be obtained. When the photoresist film is exposed to lightwith undulations on the surface, the light irradiating the photoresistpattern is scattered by the undulations (where the holes are formed) tomake it no longer possible to accurately form the grooves in theinterlayer insulating film. Particularly, because grooves may be formedin the holes (contact holes) for forming wires connecting the upper andlower wiring layers, the problem of poor processing accuracy occurs inmany of those holes.

It is true that the problem that arises when the wiring groove patternis exposed to light can be substantially dissolved by filling the holeswith an anti-reflection material. Then the anti-reflection material leftin the holes has to be removed after forming the wiring grooves.However, it is highly difficult to satisfactorily remove the filledmaterial and the material remaining in the bottoms of the contact holescan give rise to a problem of insufficient connection or increasedconnection resistance between the upper and lower wiring layers.Particularly, the problem is ever more serious in recent year as aresult of the trend of down-sizing semiconductor devices because thecontact holes are also down-sized to give rise to an increased aspectratio.

With the self-aligning method, on the other hand, wiring grooves andcontact holes are formed in a manner as described below. An interlayerinsulating film (which is not an inter-wire insulating film) is formedon the lower wiring layer and a silicon nitride film is formed thereon.Then, the silicon nitride film is subjected to a patterning process toproduce holes and, thereafter, an inter-wire insulating film (which maytypically be a silicon oxide film) is formed further thereon. In otherwords, an intermediary layer (silicon nitride film layer) processed toshow a hole pattern is formed between the interlayer insulating film andthe inter-wire insulating film. Then, a groove pattern is formed in theinter-wire insulating film. After the above process of forming thegroove pattern, the inter-wire insulating film is subjected to a processof forming holes therethrough by using the intermediary layer (thesilicon nitride film having a groove pattern) as mask. The self-aligningmethod is free from the problem of the residue of the material filled inthe holes (contact holes) and that of poor processing accuracy thatarises when the grooves are formed.

However, the intermediary layer is formed to operate as etching stopperin the process of forming the grooves (by etching) and also in theprocess of forming the holes and hence has to have a considerable filmthickness. As a result of a study made by the inventors of the presentinvention, it was found that the intermediary layer is required to be atleast about 100 nm thick if it operates properly. Silicon nitride is ahighly dielectric material and operates negatively for reducing thedielectric constant of the interlayer insulating film and that of theinter-wire insulating film. A high dielectric constant between wires orbetween wiring layers gives rise to a large inter-wire capacitance,which by turn obstructs any attempt for realizing a high performancesemiconductor device that operates at high speed. Additionally, sincethe holes are defined in the areas where both wires and holes are formedby dry etching, the holes produced there may have a reduced diameterwhen the mask for forming the holes and the one for forming the groovesare misaligned. Holes having a reduced diameter can obstruct the effortfor providing the inter-wire connection wiring with a required level ofresistance and hence again any attempt for realizing a high performancesemiconductor device that operates at high speed.

If a large groove pattern is used to avoid the misalignment of themasks, it is no longer possible to reduce both the width of the wiresand the distances separating the wiring layers to micro-dimensions.Therefore, the attempt for realizing a high performance semiconductordevice will be baffled.

In view of the above identified circumstances, therefore an object ofthe present invention is to eliminate the residue of foreign objectsthat can be left in the contact holes of a semiconductor device in orderto improve the reliability of the wire connections and the performanceof the device even when very fine dual damascene grooves are formedthere.

Another object of the present invention is to provide a technique forsecuring a sufficient area to be used for the process of forming contactholes and reducing the connection resistance between the wiring layersof a semiconductor device in order to improve the performance of thedevice.

Still another object of the present invention is to provide a techniquefor reducing the inter-wire capacitance of a semiconductor device inorder to improve the performance of the device.

Still another object of the present invention is to provide a techniquefor improving the degree of integration of a semiconductor device.

The above and other objects of the present invention as well as thenovel features of the present invention will become apparent from thedescribed made hereinafter by referring to the accompanying drawings.

Firstly, the present invention will be briefly summarized below.

With a method of manufacturing semiconductor device according to theinvention, a wiring groove pattern layer is formed on an insulatinglayer (including an interlayer insulating film and an inter-wireinsulating film) formed on a substrate so as to make it operate asetching mask when forming wiring grooves. Then, a hole pattern layer isformed on the wiring groove pattern layer to make it operate as etchingmask when forming interlayer contact holes. Thereafter, the hole patternis made to transfer into the insulating layer with a predetermined depthby means of a dry etching operation conducted on the hole pattern layer.Then, the hole pattern layer is only removed to operate the insulatinglayer with use of the hole pattern transferred on the insulating layerand of the wiring groove pattern layer as mask.

Both a semiconductor device and a method of manufacturing asemiconductor device according to the present invention are intended toprovide a wiring structure where the width of the wires is not partlyenlarged in an attempt for absorbing any possible misalignment ofinterlayer contact holes. Therefore, according to the invention, it isnow possible to reduce the inter-wire intervals to the minimal limitdefined by photolithography. Then, there may arise a problem ofmisalignment between the wiring groove pattern layer and the holepattern formed thereon. According to the invention, this misalignmentproblem can be dissolved either of the two techniques as discussedbelow. Firstly, it can be dissolved by dry etching the wiring groovepattern layer from above through the hole pattern layer beforetransferring the hole pattern into the insulating layer with apredetermined depth. Secondly it can be dissolved by using a holepattern having a hole diameter greater than the width of the wiringgrooves as measured transversally relative to the longitudinal directionof the grooves of the groove pattern and dry etching the hole patternlayer from above under the condition that the wiring groove patternlayer is not etched when transferring the hole pattern into theinsulating layer with a predetermined depth.

With a method of manufacturing a semiconductor device according to theinvention, a thin silicon nitride film having a film thickness of about50 nm is used for the wiring groove pattern layer formed on theinsulating film. Since the wiring groove pattern layer is sufficientlythin, the hole pattern layer formed thereon can be processed with asatisfactory degree of accuracy. More specifically, according to theinvention, a resist pattern (which is the pattern layer for forming thehole pattern layer) is formed on a small step as low as about 50 nm andhence the step can be made harmless simply by applying ananti-reflection film before applying resist. Therefore, unlike the abovedescribed hole-first method, no flattening operation (of filling thecontact holes with an anti-reflection material) is required.Additionally, as for the possible misalignment of the wiring groovepattern and the hole pattern, the hole pattern can be formed through thewiring groove pattern layer in the initial stages of the etchingoperation for transferring the hole pattern into the insulating layerwith a predetermined depth. It will be appreciated that, since a verythin silicon nitride film is used for the wiring groove pattern layer,the etching operation can be carried out without any difficulty. Inother words, the disadvantages of the self-aligning method can beeliminated by forming the holes firstly and securing a desired holediameter. While a problem of insufficient etching may arise at thebottoms of the holes formed through the insulating layer and showingmisalignment to a slight extent, it can be avoided by arranging anetching stopper layer under the insulating layer to accommodate apossible excessively etched condition of the holes. When, on the otherhand, using a hole pattern having a hole diameter greater than the widthof the wiring grooves as measured transversally relative to thelongitudinal direction of the grooves of the groove pattern and dryetching the hole pattern layer from above under the condition that thewiring groove pattern layer is not etched for transferring the holepattern into the insulating layer with a predetermined depth, the holepattern is transferred by etching in the areas where the wiring groovepattern and the hole pattern having holes with a diameter greater thanthe width of the wiring grooves are overlapping. Then, as the holepattern layer has holes with a diameter greater than the width of thewiring grooves to accommodate any possible misalignment of the masks,the holes will be made to show a diameter same as the width of thegrooves.

With this arrangement, the disadvantages of the hole-first methodincluding the problem of the residue of the material filled in thecontact holes can be eliminated while maintaining the advantages of themethod including the easiness of securing the contact hole diameter. Inother words, according to the invention, the hole pattern is dry etchedbefore dry etching the groove pattern so that the holes are definedfirstly particularly in terms of diameter and hence the diameter of theholes would not be reduced due to any misalignment.

As for the silicon nitride film that operates as stopper layer, it isused as etching stopper for the groove pattern and also as dry etchingmask for the hole pattern with the known self-aligning method so that itneeds to have a film thickness at least as large as 100 nm. With amethod according to the invention, on the other hand, the siliconnitride film is required to operate only as etching stopper for thegroove pattern so that it is possible to reduce the intermediary layerif compared with its counterpart used with the known self-aligningmethod. Additionally, the use of the intermediary can be avoided bycontrolling the duration of the etching operation and hence the depth ofthe hole pattern. As a result, the inter-wire capacitance of thesemiconductor device can be reduced to improve the performance of thedevice.

Various aspect of the present invention will be listed below.

1. A method of manufacturing a semiconductor device comprising:

(a) a step of forming a first insulating layer on a substrate;

(b) a step of forming a wiring groove pattern layer on the firstinsulating layer to operate as etching mask when forming wiring grooves;

(c) a step of forming a hole pattern layer on the wiring groove patternlayer to operate as etching mask when forming contact holes;

(d) a step of etching the wiring groove pattern layer and the firstinsulating layer in the presence of the hole pattern layer andtransferring the hole pattern having a predetermined depth into thefirst insulating layer;

(e) a step of removing the hole pattern layer; and

(f) a step of etching the first insulating layer in the presence of thewiring groove pattern layer and the hole pattern and transferring thewiring groove pattern into the first insulating layer.

2. A method of manufacturing a semiconductor device comprising wiringgrooves formed with a predetermined width, wires formed in the wiringgrooves and interlayer connecting members connecting the wires and lowerwires thereof arranged therebelow; said method comprising steps of:

(a) a step of forming a first insulating layer on a substrate;

(b) a step of forming a wiring groove pattern layer on the firstinsulating layer to operate as etching mask when forming wiring grooves;

(c) a step of forming a hole pattern layer on the wiring groove patternlayer to operate as etching mask when forming contact holes foraccommodating interlayer connecting members therein;

(d) a step of etching the wiring groove pattern layer and the firstinsulating layer in the presence of the hole pattern layer andtransferring the hole pattern having a predetermined depth into thefirst insulating layer;

(e) a step of removing the hole pattern layer; and

(f) a step of etching the first insulating layer in the presence of thewiring groove pattern layer and the hole pattern.

3. A method of manufacturing a semiconductor device comprising wiringgrooves formed with a predetermined width, wires formed in the wiringgrooves and interlayer connecting members connecting the wires and lowerwires thereof arranged therebelow; said method comprising steps of:

(a) a step of forming a first insulating layer on a substrate;

(b) a step of forming a wiring groove pattern layer on the firstinsulating layer to operate as etching mask when forming wiring grooves;

(c) a step of forming a hole pattern layer on the wiring groove patternlayer to make the former operate as etching mask when forming contactholes for accommodating interlayer connecting members therein with ahole diameter of the hole pattern layer substantially same as the groovewidth of the wiring groove pattern layer;

(d) a step of etching the wiring groove pattern layer and the firstinsulating layer in the presence of the hole pattern layer andtransferring the hole pattern having a predetermined depth into thefirst insulating layer;

(e) a step of removing the hole pattern layer; and

(f) a step of etching the first insulating layer in the presence of thewiring groove pattern layer and the hole pattern.

A method of manufacturing a semiconductor device as set forth in 2 or 3above, wherein the wiring groove pattern layer is partly etched with thefirst insulating layer in the etching step of (d).

5. A method of manufacturing a semiconductor device as set forth in any1 through 4 above, wherein

the hole pattern is formed to a lower portion of the first insulatinglayer in step (d) and the wiring grooves are formed in step (f).

6. A method of manufacturing a semiconductor device as set forth in anyof 1 through 4 above, wherein the hole pattern is formed halfway throughthe first insulating layer in step (d) and the wiring grooves and thecontact holes are formed in step (f).

7. A method of manufacturing a semiconductor device as set forth in anyof 1 through 6 above, further comprising;

a step of forming a second insulating layer showing an etchingselectivity relative to the first insulating layer prior to step (a);

the dry etching of step (f) being conducted in two sub-steps including afirst sub-step of etching the first insulating layer at a rate lowerthan a rate of etching the second insulating layer and a second sub-stepof etching the first insulating layer at a rate same as a rate ofetching the second insulating layer.

8. A method of manufacturing a semiconductor device comprising:

(a) a step of sequentially forming a first stopper/insulating layer, afirst insulating layer and a stopper layer;

(b) a step of transferring a wiring groove pattern into the stopperlayer;

(c) a step of forming a hole pattern layer for contact holes after step(b);

(d) a step of etching the first insulating layer halfway under conditionof removing the stopper layer and the first insulating layer in thepresence of the hole pattern layer and transferring the hole pattern;

(e) a step of removing the hole pattern layer; and

(f) a step of etching the first insulating layer in the presence of thestopper layer having the hole pattern and the wiring groove patternformed therein and forming the contact holes and the wiring grooves.

9. A method of manufacturing a semiconductor device as set forth in anyof 1 through 8 above, wherein

the hole pattern layer is formed with openings of stacked vias in step(c) and the hole pattern is formed to a lower portion of the firstinsulating layer in step (d).

10. A method of manufacturing a semiconductor device as set forth in anyof 1 through 9 above, further comprising:

a step of forming a flattening film between step (b) and step (c).

11. A method of manufacturing a semiconductor device as set forth in 10above

wherein

the flattening film is an anti-reflection film.

12. A method of manufacturing a semiconductor device as set forth in anyof 1 through 11 above, wherein the wiring grooves and the contact holesare formed in step (f) and subsequently a conductive film is buried inthe wiring grooves and the contact holes to form wires and interlayerconnecting members.

13. A method of manufacturing a semiconductor device comprising wiresformed in wiring grooves and interlayer connecting members connectingthe wires and lower wires thereof arranged therebelow; said methodcomprising:

(a) a step of sequentially forming a first stopper/insulating layer, aninterlayer insulating layer, a second stopper/insulating layer, aninter-wire insulating layer and a stopper layer;

(b) a step of transferring a wiring groove pattern into the stopperlayer;

(c) a step of forming a hole pattern mask for contact holes foraccommodating interlayer connecting members to be formed therein afterstep (b);

(d) a step of etching the inter-wire insulating layer and the secondstopper/insulating layer in the presence of the hole pattern mask andtransferring the hole pattern into the first insulating layer;

(e) a step of removing the hole pattern layer; and

(f) a step of conducting an etching operation in, the presence of thestopper layer having the hole pattern and the wiring groove patternformed therein.

14. A method of manufacturing a semiconductor device as set forth in 13above, wherein

the resist layer used for forming the wiring groove pattern is removedafter transferring the wiring groove pattern in step (b) and a holepattern mask is formed directly on the stopper layer.

15. A method of manufacturing a semiconductor device as set forth in 13or 14 above, wherein

the etching operation of step (f) is completed or terminated in thefirst stopper/insulating layer in the hole pattern region and in thesecond stopper/insulating layer in the wiring groove pattern region.

16. A method of manufacturing a semiconductor device as set forth in 13,14 or 15 above, wherein the first and second stopper/insulating layersand the stopper layer are made of silicon nitride film.

17. A method of manufacturing a semiconductor device as set forth in 16above, wherein

the stopper layer has a film thickness greater than the first and secondstopper/insulating layers.

18. A method of manufacturing a semiconductor device as set forth in anyof 13 through 17 above, wherein

the hole pattern mask is a resist mask.

19. A method of manufacturing a semiconductor device as set forth in anyof 13 through 18 above, further comprising:

a step of removing the stopper layer after the step of (f).

20. A method of manufacturing a semiconductor device as set forth in 15above, further comprising:

a step of removing the stopper layer and the first and second stopperlayers after the step of (f);

subsequently a conductive film being buried in the wiring grooves andthe contact holes to form wires and interlayer connecting members.

21. A method of manufacturing a semiconductor device comprising wiresformed in wiring grooves and interlayer connecting members connectingthe wires and the lower wires arranged therebelow; said methodcomprising:

(a) a step of sequentially forming a first stopper/insulating layer, afirst insulating layer and a stopper layer;

(b) a step of transferring a wiring groove pattern into the stopperlayer;

(c) a step of forming a hole pattern mask for contact holes foraccommodating interlayer connecting members to be formed therein;

(d) a step of etching the stopper layer and the first insulating layerin the presence of the hole pattern mask and transferring the holepattern halfway into the first insulating layer;

(e) a step of removing the hole pattern layer; and

(f) a step of conducting an etching operation in the presence of thestopper layer having the hole pattern and the wiring groove patternformed therein to form contact holes and wiring grooves.

22. A method of manufacturing a semiconductor device comprising wiresformed in wiring grooves and interlayer connecting members connectingthe wires and the lower wires arranged therebelow; said methodcomprising:

(a) a step of sequentially forming a first stopper/insulating layer, afirst interlayer insulating layer, a marker insulating layer, a secondinterlayer insulating layer and a stopper layer;

(b) a step of transferring a wiring groove pattern into the stopperlayer;

(c) a step of forming a hole pattern mask for contact holes foraccommodating interlayer connecting members to be formed therein;

(d) etching the second interlayer insulating layer and the markerinsulating layer in the presence of the hole pattern mask andtransferring the hole pattern;

(e) removing the hole pattern layer; and

(f) conducting an etching operation in the presence of the stopper layerhaving the hole pattern and the wiring groove pattern formed therein toform contact holes and wiring grooves;

the completion of the etching process of step (d) being detected bydetecting plasma light emission of the elements contained in the markerinsulating layer;

completion of the etching process on the hole pattern in step (f) beingdetected by the time of getting to the first stopper/insulating layer.

23. A method of manufacturing a semiconductor device comprising wiresformed in wiring grooves and interlayer connecting members connectingthe wires and lower wires thereof arranged therebelow; said methodcomprising:

(a) a step of sequentially forming a first interlayer insulating layer,a marker insulating layer, a second interlayer insulating layer and astopper layer;

(b) a step of transferring a wiring groove pattern into the stopperlayer;(c) a step of forming a hole pattern mask for contact holes foraccommodating interlayer connecting members to be formed therein;

(d) etching the second interlayer insulating layer and the markerinsulating layer in the presence of the hole pattern mask andtransferring the hole pattern;

(e) removing the hole pattern layer; and

(f) conducting an etching operation in the presence of the stopper layerhaving the hole pattern and the wiring groove pattern formed therein toform contact holes and wiring grooves;

completion of the etching process of step (f) being detected bydetecting plasma light emission of the elements contained in the markerinsulating layer.

24. A method of manufacturing a semiconductor device comprising wiresformed in wiring grooves and interlayer connecting members connectingthe wires and the lower wires arranged therebelow; said methodcomprising:

(a) a step of sequentially forming a first stopper/insulating layer, afirst interlayer insulating layer, a second stopper/insulating layer, asecond interlayer insulating layer, a marker insulating layer, a thirdinterlayer insulating layer and a stopper layer;

(b) a step of transferring a wiring groove pattern into the stopperlayer;

(c) a step of forming a hole pattern mask for contact holes foraccommodating interlayer connecting members to be formed therein;

(d) etching the third interlayer insulating layer, the marker insulatinglayer, the second interlayer insulating layer and the secondstopper/insulating layer in the presence of the hole pattern mask andtransferring the hole pattern;

(e) removing the hole pattern layer; and

(f) conducting an etching operation in the presence of the stopper layerhaving the hole pattern and the wiring groove pattern formed therein toform contact holes and wiring grooves simultaneously;

completion of step (f) of etching the groove pattern being detected bydetecting plasma light emission of the elements contained in the markerinsulating layer.

25. A method of manufacturing a semiconductor device comprising wiresformed in wiring grooves and interlayer connecting members connectingthe wires and the lower wires arranged therebelow; said methodcomprising:

(a) a step of sequentially forming a first interlayer insulating layer,a second interlayer insulating layer and a stopper layer;

(b) a step of transferring a wiring groove pattern into the stopperlayer;

(c) a step of forming a hole pattern mask for contact holes foraccommodating interlayer connecting members to be formed therein;

(d) etching the stopper layer and the second interlayer insulating layerin the presence of the hole pattern mask and transferring the holepattern;

(e) removing the hole pattern layer; and

(f) conducting an etching operation in the presence of the stopper layerhaving the hole pattern and the wiring groove pattern formed therein toform contact holes and wiring grooves simultaneously;

the first interlayer insulating layer and the second interlayerinsulating layer being made of respective materials showing differentetching rates;

completion of the etching process on the wiring groove pattern in step(f) being detected by the time of getting to the second interlayerinsulating layer.

26. A method of manufacturing a semiconductor device comprising wiresformed in wiring grooves and interlayer connecting members connectingthe wires and the lower wires arranged therebelow; said methodcomprising:

(a) a step of forming a first insulating layer;

(b) a step of forming a wiring groove pattern layer on the firstinsulating layer to operate as etching mask when forming wiring grooves;

(c) a step of forming a hole pattern layer on the wiring groove patternlayer to make the former operate as etching mask when forming contactholes for accommodating interlayer connecting members to be formedtherein;

(d) a step of conducting an etching operation in the presence of thehole pattern layer with a rate of etching the wiring groove patternlayer lower than the rate of etching the first insulating layer;

(e) a step of removing the hole pattern layer; and

(f) a step of conducting an etching operation in the presence of thewiring groove pattern and the hole pattern.

27. A method of manufacturing a semiconductor device as set forth in 26above, wherein

the hole diameter of the hole pattern as measured in the directiontransversal to the wiring groove pattern layer is greater than thegroove width of the wiring groove pattern layer.

28. A method of manufacturing a semiconductor device as set forth in anyof 1 through 27 above, further comprising;

(g) a step of forming a barrier metal layer and a copper layer on anentire surface of the substrate; and

(h) a step of removing the barrier metal layer and the copper layer bychemical mechanical polishing except an inside of the wiring grooves andthe contact holes formed by the etching process of step (f).

29. A method of manufacturing a semiconductor device as set forth in 28above, wherein

the wiring groove pattern layer or the stopper layer is removed in thestep of (h).

30. A method of manufacturing a semiconductor device as set forth in 29above, wherein

a mask layer for patterning the wiring groove pattern layer or thestopper layer is formed by using a conductive material.

31. A method of manufacturing a semiconductor device comprising wiresformed in wiring grooves and interlayer connecting members connectingthe wires and the lower wires arranged therebelow; said methodcomprising:

(a) a step of sequentially forming a first insulating layer and astopper layer;

(b) a step of transferring a wiring groove pattern into the stopperlayer;

(c) a step of forming a hole pattern mask for contact holes foraccommodating interlayer connecting members to be formed therein;

(d) a step of conducting a first etching operation of partly etching thestopper layer and the first insulating layer in the presence of the holepattern mask and transferring the hole pattern;

(e) a step of removing the hole pattern layer; and

(f) a step of conducting a second etching operation in the presence ofthe stopper layer having the hole pattern and the wiring groove patternformed therein to form contact holes and wiring grooves;

the stopper layer and the ridges of the first insulating layer beingetched in either or both of the first and second etching operations.

32. A method of manufacturing a semiconductor device comprising wiresformed in wiring grooves and interlayer connecting members connectingthe wires and the lower wires arranged therebelow; said methodcomprising:

(a) a step of sequentially forming a first insulating layer and astopper layer;

(b) a step of transferring a wiring groove pattern into the stopperlayer;

(c) a step of forming a hole pattern mask for contact holes foraccommodating interlayer connecting members to be formed therein;

(d) a step of conducting a first etching operation of etching part ofthe first insulating layer in the presence of the hole pattern mask andtransferring the hole pattern;

(e) a step of removing the hole pattern layer; and

(f) a step of conducting a second etching operation in the presence ofthe stopper layer having the hole pattern and the wiring groove patternformed therein to form contact holes and wiring grooves;

ends of the stopper layer being etched at least in either of the firstand second etching operations.

33. A method of manufacturing a semiconductor device as set forth in 31or 32 above, further comprising:

(g) a step of forming a barrier metal layer and a copper layer on anentire surface of the substrate; and

(h) a step of removing the barrier metal layer and the copper layer bychemical mechanical polishing except an inside of the wiring grooves andthe contact holes formed by the etching process of step (f);

parts of the copper layer and those of the barrier metal layer locatedon the wiring grooves, the stopper layer and a surface section of thefirst insulating layer being removed in the step of (h).

34. A method of manufacturing a semiconductor device as set forth in 33above, wherein

the copper layer includes a first copper layer operating as seed layerand a second copper layer formed by plating.

35. A method of manufacturing a semiconductor device comprising wiresformed in wiring grooves and interlayer connecting members connectingthe wires and lower wires thereof arranged therebelow; said methodcomprising:

(a) a step of sequentially forming a first insulating layer and astopper layer on the lower wires;

(b) a step of transferring a wiring groove pattern into the stopperlayer;

(c) a step of forming a hole pattern mask for contact holes foraccommodating interlayer connecting members to be formed therein;

(d) a step of etching the first insulating layer in the presence of thehole pattern mask and transferring the hole pattern;

(e) a step of removing the hole pattern layer; and

(f) a step of conducting a second etching operation in the presence ofthe stopper layer having the hole pattern and the wiring groove patternformed therein to form contact holes and wiring grooves;

the hole pattern mask of the step of (c) being formed in alignment withthe lower wires.

36. A method of manufacturing a semiconductor device comprising wiresformed in wiring grooves and interlayer connecting members connectingthe wires and the lower wires arranged therebelow; said methodcomprising:

(a) a step of sequentially forming a first insulating layer and astopper layer on the lower wires;

(b) a step of transferring a wiring groove pattern into the stopperlayer;

(c) a step, of forming a hole pattern mask for contact holes foraccommodating interlayer connecting members to be formed therein;

(d) a step of etching the first insulating layer in the presence of thehole pattern mask and transferring the hole pattern;

(e) a step of removing the hole pattern layer; and

(f) a step of conducting a second etching operation in the presence ofthe stopper layer having the hole pattern and the wiring groove patternformed therein to form contact holes and wiring grooves;

the hole pattern mask of the step of (c) being formed in alignment withcenter of the lower wires and that of the wiring groove pattern.

37. A method of manufacturing a semiconductor device as set forth in anyof 1 through 36 above, wherein

the plan of the contact holes is formed by transferring the plan of thehole pattern of step (c); and

the plan of the wires is formed by transferring the plan of the patternof step (b) ant that of step (c).

38. A method of manufacturing a semiconductor device as set forth in anyof 1 through 37 above, wherein

the mask of step (b) is formed by using resist or a hard mask.

39. A method of manufacturing a semiconductor device as set forth in anyof 1 through 38 above, wherein

the diameter of the contact holes and the width of the wires shows asubstantially same value.

40. A semiconductor device comprising wires formed in wiring grooves andinterlayer connecting members connecting the wires and lower wiresthereof arranged therebelow;

an interlayer insulating layer containing a marker insulating layerbeing formed to separate the lower wires and the wires in the wiringgrooves;

the marker insulating layer being formed between bottoms of the wiringgrooves and the lower wires.

41. A semiconductor device comprising wires formed in wiring grooves andinterlayer connecting members connecting the wires and lower wiresthereof arranged therebelow;

the wires having a cross section with its width increasing toward asurface so as to increase an angle of inclination.

42. A method of manufacturing a semiconductor device comprising:

a step of forming an anti-reflection film on an insulating film having aflattened surface and provided with wires arranged thereunder; and

a step of applying resist onto the anti-reflection film to form a resistfilm and irradiating the resist film with patterned light for exposure.

43. A method of manufacturing a semiconductor device as set forth in 42above, wherein

the wires are formed by burying conductive members in wiring groovesformed in a lower insulating film layer of the insulating film andremoving the conductive members by means of a CMP method from the areasother than the wiring grooves and the insulating film is formed with theflattened surface on the lower wires and the wires by means of adeposition method.

44. A method of manufacturing a semiconductor device as set forth in 42above, wherein

the wires are formed by depositing a conductive film and patterning thefilm by means of a photolithography method and the insulating film isformed with the flattened surface by depositing an insulating film tocover the wires and polishing the surface of the deposited insulating bymeans of a CMP method.

45. A method of manufacturing a semiconductor device comprising:

a step of depositing a second insulating film on a first insulatingfilm, the second insulating film showing an etching selectivity relativeto the first insulating layer;

a step of forming a first resist film patterned to show a wiring groovepattern on the second insulating film;

a step of etching the second insulating film in the presence of thefirst resist film and transferring the wiring groove pattern into thesecond insulating film;

a step of forming an anti-reflection film on the second insulating film;

a step of applying resist onto the anti-reflection film to form a secondresist film; and

a step of irradiating the second resist film with light showing acontact hole pattern for exposure.

46. A method of manufacturing a semiconductor device as set forth in 45above, wherein

the second insulating film has a film thickness small enough for thesurface thereof to be regarded as flat after forming the anti-reflectionfilm.

47. A method of manufacturing a semiconductor device as set forth in 45or 46 above, wherein

the second insulating film has a film thickness smaller than the firstinsulating and the second resist film.

48. A method of manufacturing a semiconductor device comprising:

a step of forming a mask for wiring grooves and subsequently forming ananti-reflection film;

a step of forming a mask for contact holes on the anti-reflection film;and

a step of transferring wiring grooves and contact holes into theinsulating film by using the mask for wiring grooves and the mask forcontact holes.

49. A method of manufacturing a semiconductor device as set forth in 48above, wherein

the anti-reflection film operates as flattening film.

50. A method of manufacturing a semiconductor device comprising:

a step of forming a mask for wiring grooves and subsequently forming aflattening film;

a step of forming a mask for contact holes on the flattening film; and

a step of transferring wiring grooves and contact holes into theinsulating film by using the mask for wiring grooves and the mask forcontact holes

51. A method of manufacturing a semiconductor device as set forth in 50above, wherein

the flattening film and the mask for wiring grooves are removed in aself-aligning manner relative to the mask for contact holes.

52. A semiconductor device comprising:

wiring grooves formed in an interlayer insulating film;

wires formed in the wiring grooves;

contact holes formed in the interlayer insulating film; and

connecting members formed in the contact holes;

diameter of the contact holes and width of the wires showing asubstantially same value;

the wires and the connecting members being formed integrally.

53. A semiconductor device as set forth in 52 above, wherein

the plan of the wires is formed from the plan of the contact holes andthe diameter of the contact holes as measured in the directiontransversal to the wiring grooves.

54. A semiconductor device as set forth in 52 above, wherein

the wiring grooves and the contact holes overlap with each other interms of the area of the plan of the contact holes.

55. A semiconductor device as set forth in 52, 53 or 54 above, furthercomprising:

first wires having a predetermined width greater than the diameter ofthe contact holes;

the first wires and the contact holes overlap with each other in termsof the area of the plan of the contact holes.

56. A method of manufacturing a semiconductor device comprising:

a step of forming a first mask film on a film to be patterned andsubsequently forming an anti-reflection film;

a step of forming a second mask film on the anti-reflection film; and

a step of transferring a pattern into the film to be patterned by usingthe first and second mask films.

57. A method of manufacturing a semiconductor device comprising:

a step of forming a first mask film on a film to be patterned andsubsequently forming a flattening film;

a step of forming a second mask film on the flattening film; and

a step of transferring a pattern into the film to be patterned by usingthe first and second mask films.

58. A method of manufacturing a semiconductor device as set forth in 56or 57 above, wherein

the anti-reflection film or the flattening film and the first mask filmare removed in a self-aligning manner relative to the second mask film.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross sectional view of a semiconductor deviceillustrating a step of an embodiment (Embodiment 1) of manufacturingmethod according to the invention.

FIG. 2 is a schematic cross sectional view of the semiconductor deviceof FIG. 1 showing a subsequent step of Embodiment 1 of manufacturingmethod.

FIG. 3 is a schematic cross sectional view of the semiconductor deviceof FIG. 1 showing another subsequent step of Embodiment 1 ofmanufacturing method.

FIG. 4 is a schematic cross sectional view of the semiconductor deviceof FIG. 1 showing still another subsequent step of Embodiment 1 ofmanufacturing method.

FIG. 5 is a schematic cross sectional view of the semiconductor deviceof FIG. 1 showing still another subsequent step of Embodiment 1 ofmanufacturing method.

FIG. 6 is a schematic cross sectional view of the semiconductor deviceof FIG. 1 showing still another subsequent step of Embodiment 1 ofmanufacturing method.

FIG. 7 is a schematic cross sectional view of the semiconductor deviceof FIG. 1 showing still another subsequent step of Embodiment 1 ofmanufacturing method.

FIG. 8 is a schematic cross sectional view of the semiconductor deviceof FIG. 1 showing still another subsequent step of Embodiment 1 ofmanufacturing method.

FIG. 9 is a schematic cross sectional view of the semiconductor deviceof FIG. 1 showing still another subsequent step of Embodiment 1 ofmanufacturing method.

FIG. 10 is a schematic cross sectional view of the semiconductor deviceof FIG. 1 showing still another subsequent step of Embodiment 1 ofmanufacturing method.

FIG. 11 is a schematic cross sectional view of the semiconductor deviceof FIG. 1 showing still another subsequent step of Embodiment 1 ofmanufacturing method.

FIG. 12 is a schematic cross sectional view of the semiconductor deviceof FIG. 1 showing still another subsequent step of Embodiment 1 ofmanufacturing method.

FIG. 13(a) is a schematic plan view of part of the semiconductor deviceof FIG. 1, illustrating a possible arrangement for making the wirepattern and the hole pattern overlap with each other in the case ofEmbodiment 1 of manufacturing method, FIG. 13(b) is a schematic planview of dog bones illustrated for the purpose of comparison, and FIG.13(c) is a schematic plan view of part of the semiconductor device ofFIG. 1, illustrating another possible arrangement for making the wirepattern and the hole pattern overlap with each other in the case ofEmbodiment 1 of manufacturing method.

FIG. 14 is a schematic cross sectional view of the semiconductor deviceof FIG. 1 showing still another subsequent step of Embodiment 1 ofmanufacturing method.

FIG. 15 is a schematic cross sectional view of the semiconductor deviceof FIG. 1 showing still another subsequent step of Embodiment 1 ofmanufacturing method.

FIG. 16 is a schematic cross sectional view of the semiconductor deviceof FIG. 1 showing still another subsequent step of Embodiment 1 ofmanufacturing method.

FIG. 17 is a schematic cross sectional view of the semiconductor deviceof FIG. 1 showing still another subsequent step of Embodiment 1 ofmanufacturing method.

FIG. 18 is a schematic cross sectional view of the semiconductor deviceof FIG. 1 showing still another subsequent step of Embodiment 1 ofmanufacturing method.

FIG. 19 is a schematic cross sectional view of the semiconductor deviceof FIG. 1 showing still another subsequent step of Embodiment 1 ofmanufacturing method.

FIG. 20 is a schematic cross sectional view of the semiconductor deviceof FIG. 1 showing still another subsequent step of Embodiment 1 ofmanufacturing method.

FIG. 21 is a schematic cross sectional view of the semiconductor deviceof FIG. 1 showing still another subsequent step of Embodiment 1 ofmanufacturing method.

FIG. 22 is a schematic cross sectional view of the semiconductor deviceof FIG. 1 showing still another subsequent step of Embodiment 1 ofmanufacturing method.

FIG. 23(a) is a schematic plan view of part of the wire pattern of thesemiconductor device of FIG. 1, FIG. 23(b) is a schematic crosssectional view of the wire pattern of FIG. 23(a) and FIG. 23(c) is aschematic cross sectional view of the wire pattern of FIG. 23(a).

FIG. 24(a) is a schematic plan view of part of a wire pattern of asemiconductor device illustrated for the purpose of comparison, and FIG.24(b) is a schematic cross sectional view of the wire pattern of FIG.24(a).

FIG. 25 is a schematic cross sectional view of another semiconductordevice showing a step of Embodiment 1 of manufacturing method.

FIG. 26 is a schematic cross sectional view of still anothersemiconductor device showing a step of Embodiment 1 of manufacturingmethod.

FIG. 27 is a schematic cross sectional view of still anothersemiconductor device showing a step of Embodiment 1 of manufacturingmethod.

FIG. 28 is a schematic cross sectional view of still anothersemiconductor device showing a step of Embodiment 1 of manufacturingmethod.

FIG. 29 is a schematic cross sectional view of still anothersemiconductor device showing a step of Embodiment 1 of manufacturingmethod.

FIG. 30(a) is a schematic cross sectional views of a semiconductordevice showing steps of another embodiment (Embodiment 2) ofmanufacturing method according to the invention, FIG. 30(b) is aschematic cross sectional views of a semiconductor device showing stepsof another subsequent step of Embodiment 2 of manufacturing methodaccording to the invention, and FIG. 30(c) is a schematic crosssectional views of a semiconductor device showing steps of anothersubsequent step of Embodiment 2 of manufacturing method according to theinvention.

FIG. 31(d) is a schematic cross sectional views of the semiconductordevice of FIGS. 30(a) through 30(c) showing subsequent steps ofEmbodiment 2 of manufacturing method, and FIG. 31(e) is a schematiccross sectional views of the semiconductor device of FIGS. 30(a) through30(c) showing subsequent steps of Embodiment 2 of manufacturing method.

FIG. 32(a) is a schematic cross sectional views of a semiconductordevice showing steps of still another embodiment (Embodiment 3) ofmanufacturing method according to the invention, FIG. 32(b) is aschematic cross sectional views of a semiconductor device showing stepsof still another subsequent step of Embodiment 3 of manufacturing methodaccording to the invention, and FIG. 32(c) is a schematic crosssectional views of a semiconductor device showing steps of still anothersubsequent step of Embodiment 3 of manufacturing method according to theinvention.

FIG. 33(d) is a schematic cross sectional views of the semiconductordevice of FIGS. 32(a) through 32(c) showing subsequent steps ofEmbodiment 3 of manufacturing method, and FIG. 33(e) is a schematiccross sectional views of the semiconductor device of FIGS. 32(a) through32(c) showing subsequent steps of Embodiment 3 of manufacturing method.

FIG. 34(a) is a schematic cross sectional views of a semiconductordevice showing steps of still another embodiment (Embodiment 4) ofmanufacturing method according to the invention, FIG. 34(b) is aschematic cross sectional views of a semiconductor device showing stepsof still another subsequent step of Embodiment 4 of manufacturing methodaccording to the invention, FIG. 34(c) is a schematic cross sectionalviews of a semiconductor device showing steps of still anothersubsequent step of Embodiment 4 of manufacturing method according to theinvention, and FIG. 34(d) is a schematic cross sectional views of asemiconductor device showing steps of still another subsequent step ofEmbodiment 4 of manufacturing method according to the invention.

FIG. 35(e) is a schematic cross sectional views of the semiconductordevice of FIGS. 34(a) through 34(d) showing subsequent steps ofEmbodiment 4 of manufacturing method, FIG. 35(f) is a schematic crosssectional views of the semiconductor device of FIGS. 34(a) through 34(d)showing subsequent steps of Embodiment 4 of manufacturing method, andFIG. 35(g) is a schematic cross sectional views of the semiconductordevice of FIGS. 34(a) through 34(d) showing subsequent steps ofEmbodiment 4 of manufacturing method.

FIG. 36(a) is a schematic cross sectional views of a semiconductordevice showing steps of still another embodiment (Embodiment 5) ofmanufacturing method according to the invention, FIG. 36(b) is aschematic cross sectional views of a semiconductor device showing stepsof still another subsequent step of Embodiment 5 of manufacturing methodaccording to the invention, FIG. 36(c) is a schematic cross sectionalviews of a semiconductor device showing steps of still anothersubsequent step of Embodiment 5 of manufacturing method according to theinvention, and FIG. 36(d) is a schematic cross sectional views of asemiconductor device showing steps of still another subsequent step ofEmbodiment 5 of manufacturing method according to the invention.

FIG. 37(a) is a schematic cross sectional views of a semiconductordevice showing steps of still another embodiment (Embodiment 6) ofmanufacturing method according to the invention, FIG. 37(b) is aschematic cross sectional views of a semiconductor device showing stepsof still another subsequent step of Embodiment 6 of manufacturing methodaccording to the invention, FIG. 37(c) is a schematic cross sectionalviews of a semiconductor device showing steps of still anothersubsequent step of Embodiment 6 of manufacturing method according to theinvention, FIG. 37(d) is a schematic cross sectional views of asemiconductor device showing steps of still another subsequent step ofEmbodiment 6 of manufacturing method according to the invention, FIG.37(e) is a schematic cross sectional views of a semiconductor deviceshowing steps of still another subsequent step of Embodiment 6 ofmanufacturing method according to the invention, and FIG. 37(f) is aschematic cross sectional views of a semiconductor device showing stepsof still another subsequent step of Embodiment 6 of manufacturing methodaccording to the invention.

FIG. 38(a) is a schematic cross sectional views of a semiconductordevice showing steps of still another embodiment (Embodiment 7) ofmanufacturing method according to the invention, FIG. 38(b) is aschematic cross sectional views of a semiconductor device showing stepsof still another subsequent step of Embodiment 7 of manufacturing methodaccording to the invention, FIG. 38(c) is a schematic cross sectionalviews of a semiconductor device showing steps of still anothersubsequent step of Embodiment 7 of manufacturing method according to theinvention, FIG. 38(d) is a schematic cross sectional views of asemiconductor device showing steps of still another subsequent step ofEmbodiment 7 of manufacturing method according to the invention, FIG.38(e) is a schematic cross sectional views of a semiconductor deviceshowing steps of still another subsequent step of Embodiment 7 ofmanufacturing method according to the invention, and FIG. 38(f) is aschematic cross sectional views of a semiconductor device showing stepsof still another subsequent step of Embodiment 7 of manufacturing methodaccording to the invention.

FIG. 39(a) is a schematic cross sectional views of a semiconductordevice showing steps of still another embodiment (Embodiment 8) ofmanufacturing method according to the invention, FIG. 39(b) is aschematic cross sectional views of a semiconductor device showing stepsof still another subsequent step of Embodiment 8 of manufacturing methodaccording to the invention, FIG. 39(c) is a schematic cross sectionalviews of a semiconductor device showing steps of still anothersubsequent step of Embodiment 8 of manufacturing method according to theinvention, FIG. 39(d) is a schematic cross sectional views of asemiconductor device showing steps of still another subsequent step ofEmbodiment 8 of manufacturing method according to the invention, FIG.39(e) is a schematic cross sectional views of a semiconductor deviceshowing steps of still another subsequent step of Embodiment 8 ofmanufacturing method according to the invention, and FIG. 39(f) is aschematic cross sectional views of a semiconductor device showing stepsof still another subsequent step of Embodiment 8 of manufacturing methodaccording to the invention.

FIG. 40(a) is a schematic cross sectional views of a semiconductordevice showing steps of still another embodiment (Embodiment 9) ofmanufacturing method according to the invention, FIG. 40(b) is aschematic cross sectional views of a semiconductor device showing stepsof still another subsequent step of Embodiment 9 of manufacturing methodaccording to the invention, FIG. 40(c) is a schematic cross sectionalviews of a semiconductor device showing steps of still anothersubsequent step of Embodiment 9 of manufacturing method according to theinvention, FIG. 40(d) is a schematic cross sectional views of asemiconductor device showing steps of still another subsequent step ofEmbodiment 9 of manufacturing method according to the invention, FIG.40(e) is a schematic cross sectional views of a semiconductor deviceshowing steps of still another subsequent step of Embodiment 9 ofmanufacturing method according to the invention, and FIG. 40(f) is aschematic cross sectional views of a semiconductor device showing stepsof still another subsequent step of Embodiment 9 of manufacturing methodaccording to the invention.

FIG. 41(a) is a schematic cross sectional views of a semiconductordevice showing steps of still another embodiment (Embodiment 10) ofmanufacturing method according to the invention, FIG. 41(b) is aschematic cross sectional views of a semiconductor device showing stepsof still another subsequent step of Embodiment 10 of manufacturingmethod according to the invention, FIG. 41(c) is a schematic crosssectional views of a semiconductor device showing steps of still anothersubsequent step of Embodiment 10 of manufacturing method according tothe invention, FIG. 41(d) is a schematic cross sectional views of asemiconductor device showing steps of still another subsequent step ofEmbodiment 10 of manufacturing method according to the invention. FIG.41(e) is a schematic cross sectional views of a semiconductor deviceshowing steps of still another subsequent step of Embodiment 10 ofmanufacturing method according to the invention, and FIG. 41(f) is aschematic cross sectional views of a semiconductor device showing stepsof still another subsequent step of Embodiment 10 of manufacturingmethod according to the invention.

FIG. 42(a) is a schematic cross sectional views of a semiconductordevice showing steps of still another embodiment (Embodiment 11) ofmanufacturing method according to the invention, FIG. 42(b) is aschematic cross sectional views of a semiconductor device showing stepsof still another subsequent step of Embodiment 11 of manufacturingmethod according to the invention, FIG. 42(c) is a schematic crosssectional views of a semiconductor device showing steps of still anothersubsequent step of Embodiment 11 of manufacturing method according tothe invention, FIG. 42(d) is a schematic cross sectional views of asemiconductor device showing steps of still another subsequent step ofEmbodiment 11 of manufacturing method according to the invention, FIG.42(e) is a schematic cross sectional views of a semiconductor deviceshowing steps of still another subsequent step of Embodiment 11 ofmanufacturing method according to the invention, and FIG. 42(f) is aschematic cross sectional views of a semiconductor device showing stepsof still another subsequent step of Embodiment 11 of manufacturingmethod according to the invention.

FIG. 43(a) is a schematic cross sectional views of a semiconductordevice showing steps of still another embodiment (Embodiment 12) ofmanufacturing method according to the invention, FIG. 43(b) is aschematic cross sectional views of a semiconductor device showing stepsof still another subsequent step of Embodiment 12 of manufacturingmethod according to the invention, FIG. 43(c) is a schematic crosssectional views of a semiconductor device showing steps of still anothersubsequent step of Embodiment 12 of manufacturing method according tothe invention, FIG. 43(d) is a schematic cross sectional views of asemiconductor device showing steps of still another subsequent step ofEmbodiment 12 of manufacturing method according to the invention, FIG.43(e) is a schematic cross sectional views of a semiconductor deviceshowing steps of still another subsequent step of Embodiment 12 ofmanufacturing method according to the invention, and FIG. 43(f) is aschematic cross sectional views of a semiconductor device showing stepsof still another subsequent step of Embodiment 12 of manufacturingmethod according to the invention.

FIG. 44(a) is a schematic cross sectional views of a semiconductordevice showing steps of still another embodiment (Embodiment 13) ofmanufacturing method according to the invention, and FIG. 44(b) is aschematic cross sectional views of a semiconductor device showing stepsof still another embodiment of Embodiment 13 of manufacturing methodaccording to the invention.

FIG. 45(a) is a schematic plane view of a semiconductor device showing astep of still another embodiment (Embodiment 14) of manufacturing methodaccording to the invention, FIG. 45(b 1) is a schematic cross sectionalviews of the semiconductor device of FIG. 45(a) showing subsequent stepsof Embodiment 14 of manufacturing method, FIG. 45(b 2) is a schematiccross sectional views of the semiconductor device of FIG. 45(a) showingsubsequent steps of Embodiment 14 of manufacturing method, FIG. 45(b 3)is a schematic cross sectional views of the semiconductor device of FIG.45(a) showing subsequent steps of Embodiment 14 of manufacturing method,FIG. 45(d) is a schematic cross sectional views of the semiconductordevice of FIG. 45(a) showing subsequent steps of Embodiment 14 ofmanufacturing method, FIG. 45(c 2) is a schematic cross sectional viewsof the semiconductor device of FIG. 45(a) showing subsequent steps ofEmbodiment 14 of manufacturing method, and FIG. 45(c 3) is a schematiccross sectional views of the semiconductor device of FIG. 45(a) showingsubsequent steps of Embodiment 14 of manufacturing method.

FIGS. 46(a) is a schematic plan view of the wire pattern of thesemiconductor device of FIG. 45(a), and FIG. 46(b) is a schematic crosssectional view of the wire pattern of the semiconductor device of FIG.45(a).

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, the present invention will be described in greater detail byreferring to the accompanying drawings that illustrate preferredembodiments of the invention. Throughout the drawings, same or similarcomponents are denoted respectively by same reference symbols and wouldnot be described repeatedly.

(Embodiment 1)

FIGS. 1 through 22 are schematic cross sectional views of asemiconductor device showing different steps of an embodiment ofmanufacturing method according to the invention. The steps of theembodiment will be described sequentially by referring to the drawings.

Firstly, referring to FIG. 1, a semiconductor substrate 1 typically madeof p-type single crystal silicon is brought in and device isolatingregions 2 are formed on the principal surface of the semiconductorsubstrate 1 for the device. The device isolating regions 2 are typicallyformed in a manner as described below. Firstly, a silicon oxide film(SiO₂) and a silicon nitride film (SiN) are sequentially formed on theprincipal surface of the semiconductor substrate 1. Then, the siliconnitride film is etched by using a patterned photoresist film and shallowgrooves are formed in the semiconductor substrate 1 by using the etchedsilicon nitride film as mask. Subsequently, an insulating film, whichmay typically be a silicon oxide film, is deposited to fill the shallowgrooves and all the silicon oxide film is removed, for example, by CMP(chemical mechanical polishing) or so except the areas of the shallowgrooves. As a result, the device isolating regions 2 come out.

Then, ions of impurity substances are implanted by using the patternedphotoresist film as mask to form a p-well 3 and an n-well 4. Morespecifically, ions of a p-conductivity type impurity substance such asboron (B) are implanted into the p-well 3, whereas ions of ann-conductivity type impurity such as phosphor (P) are implanted into then-well 4. Ions of impurities may subsequently and additionally beimplanted into the respective well regions in order to control thethreshold value of the MISFET.

Then, a silicon oxide film for forming a gate insulating film 5, apolycristalline silicon film for forming a gate electrode 6 and anothersilicon oxide film for forming a cap insulating film 7 are sequentiallyformed by deposition to produce a multilayer film. Then, the multilayerfilm is etched by using a photoresist film patterned by photolithographyas mask. As a result, the gate insulating film 5, the gate electrode 6and the cap insulating film 7 are made to take shape. The gateinsulating film 5 may typically be formed by thermal CVD, while the gateelectrode may be formed by CVD (chemical vapor deposition). The gateelectrode 6 may be doped with a p-type impurity or an n-type impuritydepending on the channel type of the MISFET in order to reduce theresistance of the gate electrode 6. More specifically, the gateelectrode of a p-channel type MISFET may be doped with a p-typeimpurity, whereas the gate electrode of an n-channel type MISFET may bedoped with an n-type impurity. An ion implanting technique may be usedfor the doping operation. A film of a high melting point metal silicidesuch as WSix, MoSix, TiSix or TaSix may be laid on the gate electrode 6or a layer of a metal such as tungsten may be formed on the gateelectrode 6 with a barrier metal layer of titanium nitride (TiN) oftungsten nitride (WN) interposed therebetween to reduce the sheetresistance of the gate electrode 6 and improve the operating speed ofthe MISFET. The cap insulating film 7 may typically be formed by CVD.

Then, after depositing a silicon oxide film on the semiconductorsubstrate 1 typically by CVD, the deposited silicon oxide film isanisotropically etched to produce side wall spacers 8 on the lateralwalls of the gate electrode 6. Thereafter, ions of an n-type impurity(e.g., phosphor or arsenic) are implanted into the p-well 3 by using thephotoresist film as mask to produce n-type semiconductor regions 9 atthe opposite lateral sides of the gate electrode 6 on the p-well 3. Then-type semiconductor regions 9 are formed in a self-aligning mannerrelative to the gate electrode 6 and the side wall spacers 8. The n-typesemiconductor regions 9 operate as source/drain regions of the n-channelMISFET Qn. Similarly, ions of a p-type impurity (e.g., boron) areimplanted into the n-well 4 by using the photoresist film as mask toproduce p-type semiconductor regions 10 at the opposite lateral sides ofthe gate electrode 6 on the n-well 4. The p-type semiconductor regions10 are formed in a self-aligning manner relative to the gate electrode 6and the side wall spacers 8. The p-type semiconductor regions 10 operateas source/drain regions of the p-channel MISFET Qp.

Alternatively, low concentration impurity semiconductor regions may beformed before forming the side wall spacers 8 and high concentrationimpurity semiconductor regions may be formed after forming the side wallspacers 8 to produce a so-called LDD (lightly doped drain) structure.

Then, as shown in FIG. 2, a first interlayer insulating film 11 having aflattened surface is formed on the semiconductor substrate 1 bydepositing a silicon oxide film on the 1 by means of sputtering or CVDand subsequently polishing the silicon oxide film by CMP. The firstinterlayer insulating film 11 may alternatively be a multilayer filmsuch as a silicon nitride film, an SOG (spin on glass) film or a BPSG(boron phosphor silicate lass) film.

Then, contact holes 12 are formed in the first interlayer insulatingfilm 11 by photolithography. More specifically, the contact holes areformed on the required areas of the n-type semiconductor region 9 andthe p-type semiconductor region 10.

Then, plugs 13 are formed in the respective contact holes 12 in a manneras described below. Firstly, a titanium nitride (TiN) film is formed onthe entire surface of the semiconductor substrate 1 including the insideof the contact holes 12 typically by means of CVD. Since the CVD processis excellent in covering the steps of the surface to be coated, atitanium nitride film can be formed uniformly even in the very smallcontact holes 12. Then, a tungsten (w) film is formed to fill thecontact holes 12 typically also by means of CVD because the very smallcontact holes 12 can be filled with tungsten by using a CVD process.Then, the plugs 13 are formed by removing the titanium nitride film andthe tungsten film from the areas other than those of the contact holes12 typically by CMP. Additionally, a titanium (Ti) film may be formed bydeposition before forming the titanium nitride film and thesemiconductor substrate may be silicified at the bottoms of the contactholes 12 (n-type and p-type semiconductor regions 9 and 10) by heattreatment. Such a silicide layer can effectively reduce the contactresistance of the bottoms of the contact holes 12.

Then, typically a tungsten film is formed on the entire surface of thesemiconductor substrate 1 and patterned by photolithography to producewires 14 of the first wiring layer. Such a tungsten film can be formedby CVD or sputtering.

Thereafter, as shown in FIG. 3, an insulating film such as a siliconoxide film is formed to cover the wires 14 and then flattened by CMP toproduce a second interlayer insulating film 15.

Then, a photoresist film having openings corresponding to the contactholes is formed on the second interlayer insulating film 15 and thesecond interlayer insulating film 15 is etched by using the photoresistfilm as mask to produce contact holes 16 at respective positions of thesecond interlayer insulating film 15.

Subsequently, plugs 17 are formed in the respective contact holes 16 ina manner as described below. Firstly, a barrier layer is formed on theentire surface of the semiconductor substrate 1 including the inside ofthe contact holes 16 and then a copper (Cu) film is formed to fill thecontact holes 16. The plugs 17 are produced when the copper film and thebarrier film are removed from the areas other than the contact holes 16.

The barrier layer operates to prevent the diffusion of copper intoperipheral areas including the second interlayer insulating film 15 andmay be made of titanium nitride. However, it is not necessary that thebarrier layer is made of titanium nitride and may alternatively be madeof some other metal that can effectively prevent copper from diffusioninto peripheral areas. For instance, tantalum (Ta) or tantalum nitride(TaN) may be used in place of titanium nitride. Therefore, while thefollowing steps are described below in terms of a titanium nitride filmoperating as barrier layer, the titanium nitride film may be replacedwith a tantalum film or a tantalum nitride film as described above.

The copper film operates as principal a conducting layer and can beprepared typically by plating. A thin copper film may be formed as seedfilm by sputtering prior to forming the copper film by plating. Thecopper film may alternatively be formed by sputtering. If such is thecase, the copper film formed by sputtering may be then fluidized by heattreatment to improve the effect of filling the contact holes and thewiring grooves. While the following steps are described below in termsof a copper film formed by plating, the plating process may be replacedwith a sputtering process as described above.

Then, as shown in FIG. 4, a stopper/insulating film 18 is formed on thesecond interlayer insulating film 15 and then an insulating film 19 isformed thereon for forming the second wiring layer. Thestopper/insulating film 18 operates as etching stopper when forminggrooves in the insulating film 19 and hence a material showing anetching selectivity relative to the insulating film 19 should be usedfor the stopper/insulating film 18. More specifically, thestopper/insulating film 18 may be made of silicon nitride. Theinsulating film 19 should be made of a material having a smalldielectric constant in order to minimize the inter-wire capacitance ofthe wires. The insulating film 19 may preferably be made of siliconoxide. The second wiring layer is formed in the stopper/insulating film18 and the insulating film 19 in a manner as described below. Therefore,the sum of the film thickness of the stopper/insulating film 18 and thatof the insulating film 19 is selected from the viewpoint of the secondwiring layer. Additionally, from the viewpoint of minimizing theinter-wire capacitance, the stopper/insulating film 18 made of siliconnitride that shows a high dielectric constant should be made as thin aspossible provided that it operates satisfactorily as stopper.

Then, a photoresist film having patterned openings is formed bypatterning on the insulating film 19 and the first etching operation iscarried out by using the photoresist film as mask. As a result of thefirst etching operation, the wiring grooves 20 are partly formed in theinsulating film 19. Conditions that allows the silicon oxide film to beetched with ease and makes it difficult to etch the silicon nitride filmshould be selected for the etching process. Then, the stopper/insulatingfilm 18 (silicon nitride film) can be effectively used as etchingstopper. Thereafter, the second etching operation is carried out underconditions that encourage the silicon nitride film to be etchedeffectively. Since the stopper/insulating film 18 is sufficiently thinas described above, the risk of excessively etching the secondinterlayer insulating film 15 in the second etching operation isminimized. As a result of the two-stage etching process, wiring grooves20 having a uniform depth can be reliably produced.

Then, wires 21 are formed in the respective wiring grooves 20 for thesecond wiring layer. The wires 21 has a barrier layer and a principalconducting layer, of which the barrier layer is typically made oftitanium nitride whereas the principal conducting layer is typicallymade of copper. The wires 21 are formed in a manner as described below.Firstly, a titanium nitride film is formed on the entire surface of thesemiconductor surface including the inside of the wiring grooves 20 andthen a copper film is formed to fill the wiring grooves 20. The titaniumnitride film may be formed by CVD, for example, whereas the copper filmmay be formed by plating. A thin copper film may be formed as seed filmby sputtering prior to forming the copper film by plating. Subsequently,the copper film and the titanium nitride film are removed from the areasother than the wiring grooves 20 to produce the wires 21. As pointed outabove, the barrier layer may be made of a material other than titaniumnitride, whereas the copper film may be prepared by a technique otherthan plating such as sputtering.

Then, as shown in FIG. 5, a stopper/insulating film 22, an interlayerinsulating film 23, another stopper/insulating film 24 for formingwires, another insulating film 25 for forming wires are sequentiallyformed on the wires 21 of the second wiring layer and the insulatingfilm 19. The stopper/insulating films 22, 24 are made of a materialshowing an etching selectivity relative to the interlayer insulatingfilm 23 and the insulating film 25. They may typically be made ofsilicon nitride. On the other hand, the interlayer insulating film 23and the insulating film 25 may be made of silicon oxide.

Thereafter, wiring grooves 26 are formed in the insulating film 25 andthe stopper/insulating film 24, while contact holes 27 are formed in theinterlayer insulating film 23 and the stopper/insulating film 22. Thetechnique for forming grooves 44 and holes 45 in the fifth wiring layeras discussed hereinafter for the purpose of the invention may also beused for forming the wiring grooves 26 and the contact holes 27. Sincethe technique is described in detail hereinafter in terms of the fifthwiring layer, it will not be described here.

Then, wires 28 are formed in the inside of the wiring grooves 26 and thecontact holes 27 for the third wiring layer. Connecting members forconnecting the wires 28 and the lower wires 21 are formed integrallywith the wires 28. In other words, the wires 28 are formed by way of aso-called dual damascene process in a manner as described below.Firstly, a titanium nitride film that operates as barrier layer isformed on the entire surface of the semiconductor substrate 1 includingthe inside of the wiring grooves 26 and the contact holes 27 typicallyby means of CVD and subsequently a copper film is formed to fill thewiring grooves 26 and the contact holes 27 typically by plating. Then,the copper film and the titanium nitride film are removed in areas otherthan the wiring grooves 26 and the contact holes 27 to produce the wires28 integrally with the connecting members.

Alternatively, a single damascene process may be used for the purpose ofthe invention. Then, firstly the connecting members (plugs) are formedand thereafter the wires 28 are formed in the wiring grooves as in thecase of the above described second wiring layer.

Then, as shown in FIG. 6, a stopper/insulating film 29, an interlayerinsulating film 30, another stopper/insulating film 31 for formingwires, an insulating film 32 for forming wires are sequentially formedon the insulating film 25 and the wires 28. The process of forming theinsulating films 29 through 32 is exactly same as the above describedprocess of forming the stopper/insulating film 22, the interlayerinsulating film 23, the stopper/insulating film 24 for forming wires andthe insulating film 25 for forming wires. Additionally, contact holes 33a are formed for connecting members through the stopper/insulating film29 and the interlayer insulating film 30 and then wiring grooves 33 bare formed in the stopper/insulating film 31 and the insulating film 32as in the case of the above described third wiring layer. The processfor forming the holes 33 a and the grooves 33 b can be applicable to thegrooves 44 and the holes 45 of the fifth wiring layer that will bedescribed hereinafter. Then, wires 33 are formed for the fourth wiringlayer as in the case of the wires 28 of the third wiring layer. Whilethe wires 33 of the fourth wiring layer are formed integrally with theconnecting members for connecting them with the lower layer wires 28 byway of a dual damascene process as described above, a single damasceneprocess may alternatively be used for forming the connecting members andthe wires as described above by referring to the third wiring layer.

Now, the process of forming the fifth wiring layer will be describedbelow. This is a technique for forming grooves and holes that is uniqueto the present invention. Referring to FIG. 7, insulating films 34through 38 are formed sequentially on the wires of the fourth wiringlayer and the insulating film 32 by deposition. Of the films, theinsulating films 34 and 36 are typically made of silicon nitride andhave a film thickness of 50 nm. The insulating film 35 is typically madeof silicon oxide and has a film thickness of 450 nm. The insulating film37 is typically made of silicon oxide and has a film thickness of 350nm. Finally, the insulating film 38 is typically made of silicon nitrideand has a film thickness of 100 nm.

The silicon nitride films (insulating films 34, 36, 38) may typically beformed by plasma CVD. Plasma CVD allows the use of low film formingtemperature. In the process of manufacturing a semiconductor device(so-called pre-process), the wiring forming steps are arranged close tothe end of the process so that they should be conducted at temperature(typically as low as 400° C.) that does not adversely affect the devicestructures that have already been formed (impurity diffusion layers,silicide layers, etc.). Plasma CVD is advantageous in that it canexactly meet the low temperature requirement. Additionally, the siliconoxide films (insulating films 35, 37) can be formed by plasma CVD. Whenplasma CVD is employed, TEOS (tetraethylorthosilicate) can be used assource gas. When a silicon oxide film is formed by using TEOS(hereinafter to be referred to as TEOS oxide film) as source gas, thecluster mobility can be raised at the time of forming the film toconsequently produce a silicon oxide film that is excellent in stepcoverage. Additionally, a silicon oxide film formed at relatively lowfilm forming temperature (e.g., lower than 400° C.) is very dense. Note,however, that a TEO oxide film may be replaced with an SOG (spin onglass) film showing a low dielectric constant that may contain fluorine.The use of an SOG film showing a low dielectric constant can reduce theinter-wire capacitance to improve the performance of semiconductordevices.

As described hereinafter, contact holes 45 are formed through theinsulating films 34, 35, of which the insulating film 34 operates asetching stopper when forming the contact holes 45. In other words, theinsulating film 35 is etched under conditions that make the insulatingfilm 34 resistant against etching relative to the insulating film 35.The silicon nitride film of the insulating film 34 shows a highdielectric constant relative to a silicon oxide film and hence its filmthickness should be made as small as possible in order to reduce theinter-wire capacitance. Thus, the insulating film 34 is made to show afilm thickness that is equal to the lower limit for meeting therequirements of an etching stopper that is used at the time of formingcontact holes. As pointed out above, the inter-wire capacitance of thedevice can be minimized by reducing the film thickness of the insulatingfilm 34. The above cited film thickness of 50 nm is selected by takingthese circumstances into consideration.

Wiring grooves 44 are formed in the insulating films 36, 37, of whichthe insulating film 36 operates as etching stopper when forming thewiring grooves 44 like the insulating films 34 and 35. Note that theinsulating film 36 is required to operate only as etching stopper forforming the wiring grooves and hence is not required to operate both asetching stopper form forming wiring grooves and as etching mask forforming contact holes in a manner as described earlier in terms of aself-aligning method. Therefore, the insulating film 36 can be made toshow a reduced film thickness to consequently reduce the inter-wirecapacitance if compared with a similar insulating film used with aself-aligning method. As pointed out above by referring to theinsulating film 34, the insulating film 36 is made of silicon nitrideand hence it should be made as thin as possible. The above cited filmthickness of 50 nm is selected by taking these circumstances intoconsideration.

As will be described hereinafter, the insulating film 38 operates asmask when forming wiring grooves. Since the insulating film 38 can beremoved when forming wires in a manner as described hereinafter, thefilm thickness of the insulating film 38 does not affect the inter-wirecapacitance (the performance of the device). In other words, theinsulating film 38 may have a any film thickness so long as it canoperates as mask and therefore its film thickness does not need to beminimized. The above cited film thickness of 100 nm is selected bytaking these circumstances into consideration.

While the stopper films used for forming the contact holes 45 and thewiring grooves 44 are made of silicon nitride in the above descriptionof the embodiment, they need not necessarily be made of silicon nitrideand may alternatively be made of some other material so long as thematerial shows an etching selectivity relative to a silicon oxide filmor an SOG film. For example, they may be silicon oxide films that showan etching selectivity relative to an TEOS oxide film The film thicknessof each of the silicon oxide films (insulating films 35, 37) may beselected appropriately by taking the thickness of the wires and thedistances separating the wiring layers into consideration. It should benoted here that the thickness of the wires is related with the widththereof and so determined that the cross section of each of the wiresprovides a certain required area. On the other hand, the distancesseparating the wiring layers are selected on the basis of the inter-wirewithstand voltage and the inter-wire capacitance. Thus, the filmthickness of each of the silicon oxide films is determined byconsidering those values.

Then, referring to FIG. 8, a resist film 39 is formed on the insulatingfilm 38 by photolithography. The resist film 39 is patterned to showopenings 40 a for wires and openings 40 b or stacked vias 40 b forforming wiring grooves. In other words, both a wiring groove pattern anda via pattern are formed in the insulating film 38 and the openings ofthe patterns have a width dL of 350 nm for instance.

As seen from FIG. 13(a), the openings 40 a for wires are made to show alinear profile with a same and identical width. In some instances, theopenings to be used for forming wiring grooves may be made to have aso-called dog bone sections D showing a width greater than that of thewiring grooves in areas for forming contact holes in order toaccommodate the relative displacement of the photomask for contact holesand the photomask for wiring grooves. However, such sections are notformed in this embodiment. Thus, the inter-wire intervals Sa can beminimized to improve the wire density and enhance the degree ofintegration in this embodiment. Additionally, since the openings forwires 40 a have a simple linear profile, light used for exposure duringa photolithography process would not give rise to any interference sothat the developed patterns will show an enhanced precision level.

An anti-reflection film may be formed prior to forming the resist film39. The insulating film 38 is made very flat because a CMP method isused for forming the fourth wiring layer of this embodiment and theinsulating films 34 through 38 are formed on the fourth wiring layer bymeans of CVD. However, since insulating films are generally transparentin the wavelength zone of light used for exposure, light used forexposure can get to the wires 33 of the fourth wiring layer and becomescattered by the wires 33 if no anti-reflection film is provided. Then,the accuracy of the exposure process using the resist film 39 can bedegraded by scattered light to lower the precision level of themanufacturing process. If, to the contrary, an anti-reflection film isformed on the insulating film 38, no scattered light would be producedand the accuracy of the patterning operation using the resist film 39can be significantly improved.

Thereafter, as shown in FIG. 9, a dry etching operation is carried outin the presence of the resist film 39 to transfer the wiring groovepatterns 40 a, 40 b into the insulating film 38 (and the anti-reflectionfilm if provided). The dry etching operation is conducted underconditions that allows the silicon nitride film to be etched. Forexample, a mixture gas of CHF₃, O₂ and Ar may be used as etching gaswith respective flow rates of 20, 20 and 200 sccm under the pressure of50 mTorr and RF (radio frequency) power may be applied at a rate of1,200W while keeping the substrate at temperature of 0° C. Under theseconditions, however, the rate of etching the insulating film 38 that ismade of silicon nitride will be substantially equal to the rate ofetching the underlying insulating film 37 (silicon oxide film). Then, itis no longer possible to selectively etch the insulating film 38relative to the insulating film 37. However, as pointed out above, thefilm thickness of the insulating film 38 is significantly smaller thanthat of the insulating film 27 and, therefore, the insulating film 37will be etched only slightly from the viewpoint of its large filmthickness if it is excessively etched during the operation of etchingthe insulating film 38. Thus, the etching process does not require anyetching selectivity.

When an anti-reflection film is provided, it may be etched under theconditions of using a mixture gas of CHF₃, O₂ and Ar as etching gas withrespective flow rates of 10, 90 and 950 sccm under the pressure of 750mTorr and applying RF (radio frequency) power at a rate of 900W whilekeeping the substrate at temperature of 40° C.

Then, as shown in FIG. 10, the resist film 39 is removed. As a result, awiring groove pattern layer is formed with the wiring groove patterns 40a, 40 b transferred into it. The wiring groove pattern layer is formedfrom the insulating film 38 that is a silicon nitride film.

Thereafter, as shown in FIG. 11, an anti-reflection film 41 is formed tocover the insulating film 38 that is now the wiring groove pattern layerand then a resist film 42 is formed. The anti-reflection film 41 maytypically be made of a novolac resin type organic material. Since theinsulating film 38 is made very thin in this embodiment as pointed outabove, the surface of the anti-reflection film 41 can be flattened afterfilling the groove patterns 40 (steps formed on the insulating film 38)by simply applying the material of the anti-reflection film 41, using anordinary application method. Thus, the anti-reflection film 41 is madeto become a flattened film. As a result of the provision of the flatanti-reflection film, the resist film 42 can be formed very flat toprevent any scattered light and misalignment of focal points that mayoccur if the steps on the insulating film are not hidden and improve theaccuracy of patterning the resist film 42.

Then, as shown in FIG. 12, a hole pattern 43 is formed in the resistfilm 42 by means of an ordinary photolithography technique ofirradiating the resist film with beams of light arranged to correspondto the hole pattern and developing the produced latent image of the holepattern. In this embodiment, the openings of the hole pattern 43 have adiameter of dH that is same as the width dH of the groove openings ofthe groove patterns 40 a, 40 b as show in FIG. 13(a). Therefore, if thegroove patterns 40 a, 40 b and the hole pattern 43 of the masks are notproperly aligned, some of the openings 43 will come out of thecorresponding groove openings 40 a, 40 b as shown in FIG. 13(a). Sinceit is generally highly difficult to accurately align groove patterns 40a, 40 b and a hole pattern 43, the groove patterns 40 a, 40 b and holepattern 43 of this embodiment are assumed to be displaced from eachother from the very beginning. More specifically, each of the openingsof the-hole pattern 43 of this embodiment is formed, if partly, outsidethe area where an opening of the groove patterns 40 a, 40 b is formedand hence the insulating film 38 exists. This is a major differencebetween the pattern of FIG. 13(a) and that of FIG. 13(b) where dog bonesections D are formed in the openings for wiring grooves G. In the caseof FIG. 13(b), wires have to be arranged at a pitch Pb greater than thepitch Pa of arrangement of wires of FIG. 13(a) to consequently reducethe wiring density. Additionally, because of the provision of the dogbone sections D for accommodating the relative displacement of thephotomask for contact holes and the photomask for wiring grooves, noinsulating film 38 (of silicon nitride) is formed under the openings 43.As a result, the arrangement of FIG. 13(b) requires the use of etchingconditions for forming contact holes that are different from those ofthis embodiment. Thus, the openings 43 for contact holes are transferredunder the conditions provided for etching the silicon nitride film 38 inthis embodiment while they are transferred under the conditions wherethe silicon nitride film 38 is not etched in the case of FIG. 13(b).Therefore, as described hereinafter by referring to FIGS. 17 and 22,interlayer connecting wires 50 a, 50 b are formed in the contact holes45 showing a plan view same as the openings 43 of the hole pattern andwires 49 a, 49 b are formed in the wiring grooves 44 a, 44 b showing aplan view of the sum of the groove openings 40 a, 40 b and the holeopenings 43.

Note that the line A-B in FIG. 13(a) corresponds to the line A-B in FIG.12. As seen from the drawings, the width dL of the wire openings 40 aand the vias 40 b and the diameter dH of the openings 43 of the holepattern are made equal to each other in this embodiment, the pitch ofarrangement of the wire openings 40 a and the vias 40 b can be reducedto increase the density of wires and the degree of integration ifcompared with the arrangement of FIG. 13(b). Additionally, as the holepattern 43 is transferred under the conditions same as those where theinsulating film 38 is etched, the contact holes 45 are made to show aplan same as that of the openings of the hole pattern 43 and hence adiameter equal to dH and the wires 49 a, 49 b are made to show a plansame as the sum of the plan of the openings 40 a, 40 b of the groovepattern and that of the openings 43 of the hole pattern. The net resultis a reduced resistance of the wires 49 a, 49 b. Thus, wires can bearranged at a high density and the resistance of the wires 49 a, 49 bcan be reduced in this embodiment. In the case of the vias 40 b, theplan of the via wires 49 a is made equal to the sum of the plan of theopenings 40 b of the groove pattern and that of the openings 43 of thehole pattern. In other words, each of the openings 43 of the holepattern is made to show a plan obtained by laying a via wire 49 b on acontact hole 45 so that consequently the resistance of the stacked vias49 b, or the via wires, can be reduced. Thus, the interlayer connectingwires 50 a, 50 b can be made to show a width Lw same as that of thewires 49 a, 49 b and a plan view same as that of the hole pattern 43.Additionally, as shown in FIG. 13(c), the wires 40 c including the powersupply wires for supplying the GND potential and vcc (Vcc>GND potential)and the clock wires that are wider than the wires 49 a, 49 b do notrequire any dog bone sections and are made to show a simple and linearprofile with a same width. Therefore, those wires can be processed witha high degree of precision. In short, groove patterns 40 a, 40 b and 40c as shown in FIGS. 13(a) and 13(b) are used for the embodiment.

Then, as shown in FIG. 14, an etching operation is conducted in thepresence of the resist film 42 carrying the hole pattern 43 to transferthe hole pattern 43 into the anti-reflection film 41, the insulatingfilms 37, 36 and part of the insulating film 38. The anti-reflectionfilm 41 may be etched under the conditions of using a mixture gas ofCHF₃, O₂ and Ar as etching gas with respective flow rates of 10, 90 and950 sccm under the pressure of 750 mTorr and applying RF (radiofrequency) power at a rate of 900 W while keeping the substrate attemperature of 40° C. Either of the two techniques as described belowmay be used for etching the insulating films 37, 36 and part of theinsulating film 38.

With the first technique, the hole pattern 43 as shown in FIG. 14 istransferred in a single-step etching process. The etching operation willbe conducted under conditions where the silicon nitride film and thesilicon oxide film are etched at a same etching rate. For instance, theetching operation can be conducted under the conditions of using amixture gas of CHF₃, O₂ and Ar as etching gas with respective flow ratesof 50, 10 and 500 sccm under the pressure of 50 mTorr and applying RF(radio frequency) power at a rate of 3,200W while keeping the substrateat temperature of −20° C. When such conditions are selected, theinsulating film 38 that is a silicon nitride film, the insulating film37 that is a silicon oxide film and the insulating film 36 that is asilicon nitride film will be etched at a same rate. The etching depth(the depth of the openings 43 of the hole pattern) can be controlled bycontrolling the duration of the etching process.

The second technique, on the other hand, is a three-step etching processincluding a first step of removing part of the insulating film 38 underconditions where silicon nitride film can be etched, a second step ofetching the insulating film 37 under conditions where silicon oxide filmcan be selectively etched but silicon nitride film is hardly etched anda third step of etching the insulating film 36 under conditions good foretching silicon nitride film. The depth of etching using the holepattern 43 can be easily controlled with such a three-step process. Morespecifically, since the second step is an selective etching operation,the insulating film 36 can be used as etching stopper for the etchingoperation of the second step. Then, the depth of etching using the holepattern 43 can be uniformed without the need of time control. Theetching operations of the first and third steps may be conducted underthe conditions of using a mixture gas of C₄F₈, O₂ and Ar as etching gaswith respective flow rates of 12, 7 and 400 sccm under the pressure of30 mTorr and applying RF (radio frequency) power at a rate of 3,400Wwhile keeping the substrate at temperature of 0° C., whereas the etchingoperation of the second step may be conducted under the conditions ofusing a mixture gas of CHF₃ and O₂ as etching gas with respective flowrates of 20 and 20 sccm under the pressure of 50 mTorr and applying RF(radio frequency) power at a rate of 1,200W while keeping the substrateat temperature of 0° C.

With either of the above two techniques, holes are cut through theinsulating film 38 on the basis of the hole pattern 43. In other words,if the hole pattern 43 and the groove patterns 40 a, 40 b are displacedfrom each other, the hole pattern 43 is aligned with the groove patterns40 a, 40 b in a self-aligning manner so that the diameter of theopenings of the holes can be held to the designed value of dH. Since thediameter dH of the openings of the holes is held to the designed valueof dH regardless of the locations of the wiring grooves, the problem ofa reduced diameter of contact holes of the known self-aligning method iseliminated by the present invention.

As pointed out above, with either of the above two techniques, holes arecut through the insulating film 38 on the basis of the hole pattern 43.In other words, the hole pattern 43 is transferred into the insulatingfilm 36. This is for forming contact holes at the time of the etchingoperation of forming wiring grooves as described hereinafter. Morespecifically, when wiring grooves are formed by etching the insulatingfilm 37, the insulating film 35 is also etched in areas corresponding tothe openings of the hole pattern 43 to produce part of the contact holessimultaneously with the wiring grooves if holes are cut through theinsulating film 38 on the basis of the hole pattern 43. This will bediscussed in greater detail hereinafter.

It should be noted that, with the above first technique, the bottoms ofthe holes formed by the hole pattern 43 may produce steps S if the holepattern 43 and the groove patterns 40 a, 40 b are misaligned. However,the etching depth is uniformed at the bottoms of the holes as theinsulating film 34 operates as etching stopper and therefore no problemoccurs there as described below.

Then, as shown in FIG. 15, the resist film 42 and the anti-reflectionfilm 41 are removed typically by means of an ashing technique. At thisstage of operation, the groove patterns 40 a, 40 b are transferred tothe insulating film 38 (groove pattern layer) and the hole pattern 43 istransferred to the insulating films 36, 37 and part of the insulatingfilm 38.

Thereafter, as shown in FIG. 16, an etching operation is conducted inthe presence of the groove patterns 40 a, 40 b and the hole pattern 43to transfer the groove patterns 40 a, 40 b and the hole pattern 43respectively to the insulating film, 37 and the insulating film 35. As aresult, part of the wiring grooves 44 a, 44 b and the contact holes 45are formed. In other words, the areas other than the wiring groovesformed by using the groove patterns 40 a, 40 b and the holes formed byusing the hole pattern 43 are filled with the insulating film 38 so thatthe latter operates as mask and the insulating film 37 is etched inareas other than the groove patterns 40 a, 40 b. The insulating film 35is also etched because holes are already formed in the insulating films37, 36 by the hole pattern 43. The etching operation proceedssimultaneously in the regions of the groove patterns and that of thehole pattern to produce part of the wiring grooves 44 a, 44 b and thecontact holes 45 simultaneously. The contact holes 45 show a plan viewsame as those of the openings of the hole pattern 43 and hence adiameter equal to Lw, which is substantially equal to the width of thewiring grooves 44 a, 44 b. Then, as a result, the resistance of thewires 49 a, 49 b is reduced.

The etching operation is conducted conditions where silicon oxide filmcan be selectively etched but silicon nitride film is hardly etched. Forexample, the etching operation can be conducted under the conditions ofusing a mixture gas of C₄F₈, Ar, O₂ and CO as etching gas withrespective flow rates of 20, 500, 9, and 100 sccm under the pressure of30 mTorr and applying RF (radio frequency) power at a rate of 3,600Wwhile keeping the substrate at temperature of −20° C.

When such conditions are selected, silicon nitride film is hardly etchedwhile silicon oxide film is easily etched so that the insulating film 36operates as stopper for etching the grooves while the insulating film 34operates as stopper for etching the holes. As a result, the grooves andthe holes are made to show respective uniform depths if the film layersare etched excessively to a slight extent. Additionally, it is no longernecessary to control the depth of the grooves and that of the holes bycontrolling the duration of the etching process for the operation offorming them by etching. Still additionally, it is not necessary toterminate the operation of forming the grooves by etching at the bottomsthereof and that of forming the holes at the bottoms thereofsimultaneously. In other words, the operation of forming the grooves maybe terminated before forming the holes or vice versa. If the bottoms ofthe holes 43 shows steps S as described above, they are eliminated whenthe film layer accommodating the bottoms thereof are excessively etchedto make the bottoms flat.

However, it is preferably that the film thickness of the insulating film35 and that of the insulating film 37 are optimized so that theoperation of forming the grooves by etching and that of forming theholes may be terminated simultaneously. If the operations are terminatedsimultaneously, the insulating films 34, 36 that are silicon nitridefilms showing a high dielectric constant and operating as stoppers maybe made to have a reduced film thickness to consequently reduce theinter-wire capacitance of the device.

Then, as shown in FIG. 17, an etching operation is conducted underconditions good for etching silicon nitride film to etch the insulatingfilm 38, the insulating film 36 where the bottoms of the grooves 44 a,44 b are located and the insulating film 34 where the bottoms of theholes 45 are found. As a result, the process of forming the wiringgrooves 44 a, 44 b and the contact holes 45 is completed. For theetching operation, for example, a mixture gas of CHF₃, O₂ and Ar may beused as etching gas with respective flow rates of 20, 20 and 400 sccm or600 sccm under the pressure of 50 mTorr and RF (radio frequency) powermay be applied at a rate of 1,200W while keeping the substrate attemperature of 0° C. While the silicon oxide films may be etched by thisetching operation, no problems will arise if they are is etchedexcessively to a slight extent because the insulating films 38, 36, 34have a film thickness significantly smaller than that of the insulatingfilm 35. Additionally, while the insulating film 38 has a film thicknessrelatively greater than those of the insulating films 36, 34, its filmthickness is reduced when it is used as mask for forming the grooves andthe holes simultaneously by etching so that it can be removed easilyduring this etching operation.

Note that this etching operation is required to remove the insulatingfilm 34 from the bottoms of the contact holes 45 and the insulatingfilms 36, 38 do not need to be removed by this etching operation. Inother words, this etching operation is conducted to complete the processof forming the contact holes 45 and the purpose of the operation isachieved when the contact holes 45 are completely formed. However, sincethe insulating films 36, 38 are etched simultaneously with theinsulating film 34 as pointed out above, the silicon nitride filmshowing a high dielectric constant and left on the bottoms of the wireswill also be removed to reduce the inter-wire capacitance of the devicewhen the insulating film 36 is etched out. Additionally, the inter-wirecapacitance of the device will also be reduced when the insulating film38 is removed. Thus, the etching operation can provide such auxiliaryeffects.

Thereafter, a barrier metal layer 46 is formed as shown in FIG. 18. Thebarrier metal layer 46 prevents any possible diffusion of copper that isthe principal ingredient of the wires and the interlayer connectingwires and, at the same time, improves the mutual adhesion of copperwires and the silicon oxide films. The barrier metal layer 46 maytypically be made of tantalum (Ta). When the barrier metal layer 46 ismade of tantalum film, the film thickness is preferably about 100 nmwhen laid on the insulating film 37 (flat above the substrate). Tantalumnitride (TaN) or titanium nitride (TiN) may alternatively be used forthe barrier metal layer 46. Any of such metal compounds may be used forthe barrier metal layer 46 so long as it can effectively prevent thepossible diffusion of copper. The barrier metal layer 46 may be formedby using a long throw sputtering technique with which the target and thesubstrate are separated by about 200 nm. With such a technique, thebarrier metal layer 46 can be formed on the very small bottoms of thecontact holes 45 with a relatively uniform film thickness. In place ofthe long throw sputtering method, a CVD method or an ordinary sputteringmethod may alternatively be used for the purpose of the presentinvention.

Then, as shown in FIG. 19, a seed layer 47 is formed on the barriermetal layer 46. The seed layer 47 is made of copper and operates as seedfor forming a plated copper layer which will be described hereinafter.While a long throw sputtering method may also be used for forming theseed layer 47, a CVD method or an ordinary sputtering method mayalternatively be used. The seed layer 47 is made to have a thickness ofabout 100 nm when laid flat above the substrate.

Thereafter, as shown in FIG. 20, a copper plating layer 48 is formed.The copper layer 48 may be formed either by electrolytic plating or bynon-electrolytic plating. The copper plating layer 48 is made to have athickness of about 300 nm when laid flat above the substrate. As aresult, both the wiring grooves 44 a, 44 b and the contact holes 45 arefilled.

While the copper film (copper plating layer 48) is formed by means of aplating technique in this embodiment, it may alternatively be formed bysputtering. Then, the seed layer 47 is not necessary. When the copperfilm is formed by sputtering, the copper of the film can be made toreflow and fill the contact holes and the wiring grooves 44 a, 44 b byheat treatment.

Then, as shown in FIG. 21, the copper plating layer 48 and the seedlayer 47 are polished by CMP. Since a copper film can be polished andscraped off at a high rate, the copper will be removed first by thepolishing operation.

As the polishing operation is continued, the barrier metal layer 46(tantalum film) on the insulating film 37 is removed as shown in FIG.22. As a result, the barrier metal layer 46 and the copper film(including the copper plating layer 48 and the seed layer 47) areremoved except the inside of the wiring grooves 44.

For the polishing operation using a CMP technique, polishing slurrycontaining an oxidizing agent such as hydrogen peroxide and aluminagrains may be used. The copper film and the barrier metal layer(tantalum film) may be polished and scraped off collectively by means ofa single and same platen. The time required for the polishing operationis 3 minutes including 2.5 minutes for completely removing the barriermetal layer 46 (100% polishing) and 0.5 minutes for excessive polishing.After the polishing operation using a CMP technique, the slurry grainsand the copper adhering to the surface of the wafer can be removed by atwo-stage brush scrubbing process of washing the device with an aqueoussolution containing ammonium to a concentration of 0.1% and subsequentlywith pure water.

Now, the process of forming the interlayer connecting wires 50 a, 50 bfor connecting the wires 49 a, 49 b of the fifth wiring layer and thewires 33 of the fourth wiring layer is completed. It may be clear fromthe above description that the wires 49 a, 49 b are formed integrallywith the interlayer connecting wires 50 a, 50 b. Thus, the width Lw ofthe interlayer connecting wires 50 a, 50 b can be made substantiallyequal to the width Lw of wires 49 a, 49 b. The plan view of theinterlayer connecting wires 50 a, 50 b is defined by the hole pattern 43and the plan view of the wires 49 a, 49 b is defined as a sum of thegroove patterns 40 a, 40 b and the hole pattern 43.

Thereafter, additional wiring layers including the sixth wiring layermay be formed in a manner as described above but they will not bedescribed any further. As pointed out above, the wires 28 of the thirdwiring layer and the wires 38 of the fourth wiring layer can be formedby using the above described process for forming the wires 49 a, 49 b ofthe fifth wiring layer. It may be appreciated that the wires of thefirst wiring layer and those of the second wiring layer can also beformed by using the process for forming the wires 49 a, 49 b of thefifth wiring layer.

Thus, this embodiment can be provided with highly reliable micro-wiresand a low inter-wire capacitance in addition to the advantages describedabove in terms of the manufacturing steps. More specifically, thecontact holes can be formed with a diameter equal to that of theopenings of the hole pattern as in the case of the hole-first method tomake the interlayer connecting wires show a designed cross section. Onthe other hand, unlike the hole-first method, it is not necessary tofill the deep holes with resist or an anti-reflection material. As aresult, the problem of reduced reliability due to the resist of theanti-reflection material left in the holes is completely eliminated. Onthe other hand, since the insulating film 36 operating as intermediarystopper of the above described embodiment can be made to show a reducedfilm thickness, the embodiment is free from the problem of increasedinter-wire capacitance of the self-aligning method. Additionally, thepitch of arrangement of the wires 49 a, 49 b can be reduced to raise thewire density and the degree of integration of the device by forming theopenings of the hole pattern 43 with a diameter of H that is equal tothe width dL of the openings dL of the groove patterns 40 a, 40 b. Stilladditionally, the interlayer connecting wires 50 a, 50 b can be made toshow a plan view conforming to that of the hole pattern 43 to reduce theresistance of the wires 49 a, 49 b by forming the hole pattern 43 afterforming the groove patterns 40 a, 40 b and transferring the hole pattern43 onto the groove pattern 40 a, 40 b that is by etching the siliconnitride film 38 according to the plan of the hole pattern 43. In short,the pitch of arrangement of the wires can be reduced to raise the wiredensity and the degree of integration of the device and the resistanceof the wires 49 a, 49 b can be reduced in the above describedembodiment.

While the process of forming contact holes by using the hole pattern 43of this embodiment is terminated halfway before getting to the bottom ofthe insulating film 35 as shown in FIG. 14, it may alternatively be madeto proceed until the contact holes get to the surface of the insulatingfilm 34. In such a case, as shown in FIG. 25, the insulating film 34(silicon nitride film) can be used as mask when removing the resist film42 and the anti-reflection film 41 as in the case of FIG. 15 (FIG. 26).If the operation of transferring the groove patterns 40 a, 40 b as shownin FIG. 16 is conducted under the condition of FIG. 26 in order totransfer them into the insulating film 37, the insulating film 34 willoperate as etching stopper.

Of the wires, the stacked vias 49 b connecting the upper and lower wiresmay be formed without using a groove pattern for forming wiring grooves.More specifically, as shown in FIG. 27, the wires for connecting theupper and lower wires are formed without a patterning operation and onlythe wiring pattern 51 of the wiring layer is formed. Then, as shown inFIG. 28, a resist film 53 provided with openings 52 a, 52 b are formed.Thereafter, the etching operation of FIG. 14 is conducted in thepresence of the resist film 53. Since the insulating film 38 is etchedunder conditions where silicon nitride film is etched in this etchingoperation, the insulating film 38 may be formed under the openings 52 bas shown in FIG. 29 without any problem. In such a case, any possiblemisalignment of the wiring groove pattern 40 b to be used for connectingthe upper and lower wires and the contact hole pattern 43 does notrequire particular consideration so that the process can be simplifiedand the resistance of the vias 49 b can be held low.

FIG. 23(a) shows a schematic plan view of part of the wire pattern ofthe wires 49 a of this embodiment. FIG. 23(b) and FIG. 23(c) areschematic cross sectional views of the wire pattern of FIG. 23(a) takenalong line A-B and line C-D of FIG. 23(a) respectively. As shown, as thepitch Pa of arranging the wires is reduced, the diameter dh of thecontact holes 50 a is made smaller than the diameter W to reduce theresistance of the contact holes. Thus, the degree of integration of thedevice can be raised while the resistance of the contact holes isreduced.

FIG. 24(a) is a schematic plan view of part of a wire pattern of asimilar semiconductor device for forming wires 49 a as illustrated forthe purpose of comparison. Of this semiconductor device, the contactholes are formed by a self-aligning method (and hence the siliconnitride film 38 is not etched in the step of FIG. 14). FIG. 24(b) is aschematic cross sectional view of the wire pattern of FIG. 24(a). If thehole pattern 43 is not accurately aligned with the wires 49 a, thecontact holes are formed in areas where the hole pattern 43 and thewires 49 a are laid one on the other. As a result, the diameter d′ ofthe contact holes is made smaller than the diameter d of the openings ofthe hole pattern 43 (d′<d) to raise the resistance of the contact holes.If the diameter of the openings of the hole pattern 43 is reduced toavoid this problem, the pitch Pc of arranging the wires 49 a should beincreased to become greater than the pitch Pa of this embodiment(P-channel>Pa) in order to accommodate the misalignment of the patterns.Note, however, the use of a self-alignment method provides an advantagethat the corresponding etching operation can be simplified and carriedout in a single etching step.

(Embodiment 2)

FIGS. 30(a) through 30(c) are schematic cross sectional views of asemiconductor device showing steps of another embodiment (Embodiment 2)of manufacturing method according to the invention. FIGS. 31(d) and31(e) are schematic cross sectional views of the semiconductor device ofFIGS. 30(a) through 30(c) showing subsequent steps of Embodiment 2 ofmanufacturing method. Note that only a left half of the semiconductordevice corresponding to the fifth wiring layer of Embodiment 1 is shownin FIGS. 30(a) through 31(e) in a simplified fashion.

This embodiment of manufacturing method according to the invention isidentical with Embodiment 1 in terms of the steps illustrated in FIG. 1through FIG. 12. Thereafter, as shown in FIG. 30(a), insulating films 34through 38 are sequentially formed on the fourth wiring layer and afteretching the insulating film 38, using the groove pattern 40, ananti-reflection film 41 and a resist film 42 are formed. Then, a holepattern 43 is formed in the resist film 42. Note that, in thisembodiment again, the hole pattern 43 is misaligned with the groovepattern 40 as shown in FIG. 13(a).

Then, as shown in FIG. 30(b), an etching operation is conducted in thepresence of the resist film 42 carrying the hole pattern 43. Theanti-reflection film 41 is etched under conditions same as thosedescribed above in terms of Embodiment 1. However, the insulating film36 is etched under conditions different from those described above interms of Embodiment 1. More specifically, it is etched under conditionswhere silicon nitride film is hardly etched. For example, a mixture gasof CHF₃ and O₂ may be used as etching gas with respective flow rates of20 and 20 sccm under the pressure of 50 mTorr and RF (radio frequency)power may be applied at a rate of 1,200W while keeping the substrate attemperature of 0° C. Since silicon nitride film is etched while siliconnitride film is hardly etched under these conditions, the insulatingfilm 38 will not be etched and operate as etching mask with the resistfilm 42 for etching the insulating film 37. Therefore, the insulatingfilm 37 is not etched in areas where it is covered by the insulatingfilm 38 (silicon nitride film) and hence the holes 43 are formed in aself-aligning manner relative to the insulating film 38 in areas wherethe hole pattern 43 and the groove pattern 40 are displaced from eachother. Thus, the contact holes are not found outside the wiring grooves.In other words, the mask for the wiring groove and the mask for thecontact holes are not displaced from each other if the wires are denselyarranged and separated with small intervals.

In this embodiment again, the hole pattern 43 has to be transferred intothe insulating film 36 and therefore the insulating film 36 has to beetched under conditions where silicon nitride film is easily etched.Thus, with this embodiment, the hole pattern 43 is transferred into theinsulating films 37, 37 in two steps including the first step conductedunder conditions where silicon nitride film is hardly etched and thesecond step conducted under conditions where silicon nitride film iseasily etched.

Then, the resist film 42 and the anti-reflection film 41 are removed asin the step of FIG. 15 of Embodiment 1 (FIG. 30(c)) and thereafter thegroove pattern 40 is transferred into the insulating film 37 for thewiring grooves while the hole pattern 43 is transferred into theinsulating film 35 as in the step of FIG. 16 of Embodiment 1 (FIG.31(d)). Thereafter, as shown in FIG. 31(e), the insulating film 38 thatis a silicon nitride film, the insulating film 36 found on the bottomsof the wiring grooves 44 and the insulating film 34 found on the bottomsof the contact holes 45 are removed to produce the wiring grooves 44 andthe contact holes 45. The subsequent steps are same as those ofEmbodiment 1.

Thus, with this embodiment of manufacturing method, the contact holes 45are formed in a self-aligning manner relative to the wiring grooves 44to improve the density of arranging wires.

(Embodiment 3)

FIGS. 32(a) through 32(c) are schematic cross sectional views of asemiconductor device showing steps of still another embodiment(Embodiment 3) of manufacturing method according to the invention. FIGS.33(d) and 33(e) are schematic cross sectional views of the semiconductordevice of FIGS. 32(a) through 32(c) showing subsequent steps ofEmbodiment 3 of manufacturing method. Note that only a left half of thesemiconductor device corresponding to the fifth wiring layer ofEmbodiment 1 is shown in FIGS. 32(a) through 33(e) in a simplifiedfashion to show the left half of the device as show in FIGS. 1 trough29.

This embodiment of manufacturing method according to the invention isidentical with Embodiment 1 in terms of the steps illustrated in FIG. 1through FIG. 12. Thereafter, as shown in FIG. 32(a), insulating films 34through 38 are sequentially formed on the fourth wiring layer and afteretching the insulating film 38, using the groove pattern 40, ananti-reflection film 41 and a resist film 42 having a hole pattern 43are formed. Note that, in this embodiment, the hole pattern 43 is notmisaligned with the groove pattern 40 (FIG. 32(a)).

Then, as shown in FIG. 32(b), an etching operation is conducted in thepresence of the resist film 42 carrying the hole pattern 43, by usingthe resist film as mask. The anti-reflection film 41 is etched underconditions same as those described above in terms of Embodiment 1. As aresult of the etching operation, the hole pattern 43 is transferred intothe insulating films 37, 36. The etching operation may be conductedeither in one step where the insulating films 37, 36 are etchedconsecutively under conditions good for etching silicon nitride film orin two steps including the first step conducted under conditions wheresilicon oxide film is easily etched but silicon nitride film is hardlyetched and the second step conducted under conditions where siliconnitride film is etched. The conditions good for etching silicon nitridefilm, those where silicon oxide film is easily etched but siliconnitride film is hardly etched may be same as those described earlier.

In this-embodiment again, the hole pattern 43 has to be transferred intothe insulating film 36.

Then, the resist film 42 and the anti-reflection film 41 are removed asin the step of FIG. 15 of Embodiment 1 (FIG. 32(c)) and thereafter thegroove pattern 40 is transferred into the insulating film 37 for thewiring grooves while the hole pattern 43 is transferred into theinsulating film 35 as in the step of FIG. 16 of Embodiment 1 (FIG.33(d)). Thereafter, as shown in FIG. 33(e), the insulating film 38 thatis a silicon nitride film, the insulating film 36 found on the bottomsof the wiring grooves 44 and the insulating film 34 found on the bottomsof the contact holes 45 are removed to produce the wiring grooves 44 andthe contact holes 45. The subsequent steps are same as those ofEmbodiment 1.

(Embodiment 4)

FIGS. 34(a) through 34(d) and 35(e) through 35(g) are schematic crosssectional views of a semiconductor device showing steps of still anotherembodiment (Embodiment 4) of manufacturing method according to theinvention. Note that only a left half of the semiconductor devicecorresponding to the fifth wiring layer of Embodiment 1 is shown inFIGS. 34(a) through 34(d) in a simplified fashion to show the left halfof the device as shown in FIGS. 1 through 29 as in Embodiment 2.

This embodiment of manufacturing method according to the invention isidentical with Embodiment 1 in terms of the steps illustrated in FIG. 1through FIG. 15. Thereafter, insulating films 34 through 38 aresequentially formed on the wires 33 of the fourth wiring layer and theinsulating film 32 and then a groove pattern 40 is formed on theinsulating film 38. Subsequently, the hole pattern 43 is transferredinto the insulating films 37, 36, by using a resist film carrying a holepattern 43, which resist film is then removed (along with theanti-reflection film) (FIG. 34(a)).

Note, however, that the insulating film 38 has a film thickness of 70nm, which smaller than the film thickness (100 nm) of its counterpart ofEmbodiment 1.

Then, as shown in FIG. 34(b), the groove pattern 40 of the wiringgrooves and the hole pattern 43 are transferred respectively into theinsulating film 37 and the insulating film 35. The etching conditionsused for the transfer operation are identical with those described abovefor Embodiment 1. Since the insulating film 38 has a relatively smallfilm thickness of 70 nm, it is etched at end portions thereof to becomerecessed by the etching operation of the transfer step. As a result, thegrooves 40 of the insulating film 38 are made to have sloping shoulders54 as shown in FIG. 34(b). After the transfer of the groove-pattern 40into the insulating film 37, when the bottoms of the grooves 40 of theinsulating film 36 come to be exposed, the insulating film 36 is alsoexposed to the etching atmosphere. If the etching operation is continuedunder this condition, the insulating film 36 is also etched at endportions thereof to become recessed and the holes 43 of the insulatingfilm 36 are made to have sloping shoulders 55.

As the shoulders 54, 55 are formed, the openings of the wiring groovesand those of the contact holes are enlarged so that they can easily befilled with metal film. Note that the shoulders 54, 55 show a crosssection whose width is increasing toward the surface so as to increasethe angle of inclination as a result of the recessed end portions of themasks due to the etching operations.

Then, as shown in FIG. 34(c), the insulating film 38, the insulatingfilm 36 on the bottoms of the grooves 40, and the insulating film on thebottoms of the holes 43 are removed by etching to complete the operationof forming the wiring grooves 44 and the contact holes 45. The etchingconditions used for the above etching operation are identical with thosedescribed above for Embodiment 1.

Thereafter, a barrier metal layer 46 is formed as in the step of FIG. 18of Embodiment 1 (FIG. 34(d)) and then a seed layer 47 and a copperplating layer 48 are formed as in the steps of FIGS. 19 and 20 ofEmbodiment 1 (FIG. 36(e)). Since the shoulders 54, 55 of the openings ofthe contact holes 45 and the wiring grooves 44 of this embodiment arerounded, the barrier metal layer 46 and the seed layer 47 can besputtered with ease. Additionally, the copper plating layer 48 caneasily be made to fill the grooves and the holes because of theshoulders.

Then, as shown in FIG. 35(f), the copper plating layer 48 and the seedlayer 47 are scraped by CMP as shown in FIG. 35(f) and then the barriermetal layer 46 is also removed by CMP as shown in FIG. 35(g).

Note, however, the CMP process of this embodiment is not terminated whenthe barrier metal layer 46 on the insulating film 37 is removed (justscraped off) but conducted excessively until an upper portion of theinsulating film 37 is also removed. More specifically, the excessivepolishing operation is conducted until the width of the shoulders 54 ofthe wiring grooves 44 becomes smaller than a predetermined value. As aresult of the excessive polishing operation, the rounded areas of theshoulders 54 are removed to reduce the width of the wires in order toeliminate the risk of short-circuiting of the wires and that of reducingthe withstand voltage of the wires. In other words, if the rounded areasof the shoulders 54 are left unremoved when the polishing operation isterminated, the intervals separating the wires are reduced by therounded areas of the shoulders 54 to raise the risk of short-circuitingof the wires and that of reducing the withstand voltage of the wires.Thus, the operation of excessively polishing the surface of theinsulating film 37 of this etching mask that continues until theshoulders 54 are removed to a large extent, the width of the wires isreduced to eliminate that above identified risks.

All the subsequent steps of this embodiment are identical with those ofEmbodiment 1.

Thus, this embodiment provides the advantage of broadening the openingsof the wiring grooves 44 and those of the contact holes 45 so that thebarrier metal layer 46, the seed layer 47 and the plating layer 48 canbe formed to fill the wiring grooves and the contact holes with ease.

Another advantage of this embodiment is that wires are formed byexcessively using the CMP process to remove the broadened portions ofthe wiring grooves 44 and widen the intervals separating the wires inorder to reduce the inter-wire leak current and improve the withstandvoltage.

While the metal wiring layers are formed by means of a plating techniquein this embodiment, they may alternatively be formed by means of areflow technique of combining sputtering and heat treatment. The use ofa reflow technique is advantageous for forming shoulders 54, 55 (roundedareas) because they improve the mobility of metal and make the wiringgrooves and the contact holes to be effectively filled with metal.

(Embodiment 5)

This embodiment differs from Embodiment 4 in terms of the technique usedfor forming the shoulders 54, 55. In other words, the shoulders 54, 55of Embodiment 4 can be formed by a technique as illustrated in FIG. 36.FIGS. 36(a) through 36(d) are schematic cross sectional views of asemiconductor device showing steps of still another embodiment(Embodiment 5) of manufacturing method according to the invention.

More specifically, the groove pattern 40 is transferred into theinsulating film 37 as described above for Embodiment 1 by referring toFIG. 16 (FIG. 36(a)). The etching operation of forming holes 43 isterminated before they get to the insulating film 34. Additionally, theinsulating film 38 is made to have a sufficiently large film thickness(e.g., 100 nm) so that the insulating film 37 may not be removed alongthe edges of the wiring grooves 40.

Then, as shown in FIG. 36(b), the insulating film 38 and the insulatingfilm 36 are partly etched under conditions good for etching siliconnitride film. As a result of this etching operation, the insulating film38 and the insulating film 36 are etched along the edges 56 of thewiring grooves and the contact holes.

As shown in FIG. 36(c), the etching conditions are modified to allowsilicon oxide film to be easily etched but make silicon nitride to behardly etched and the etching operation is continued. Since no siliconnitride film is found along the edges 56 of the grooves and the openingscut into the insulating film 38 and the insulating film 36, the edges 56do not operate as etching mask. Additionally, the silicon nitride filmlocated adjacent to the edges is very thin, shoulders 57 are formedalong the edges.

Thereafter, as shown in FIG. 36(d), the insulating film 38, theinsulating film 36 left on the bottoms of the wiring grooves 40 and theinsulating film 34 left on the bottoms of the contact holes 43 areremoved by etching to complete the operation of producing the wiringgrooves 44 and the contact holes 45. All the subsequent steps of thisembodiment are identical with those of Embodiment 4.

Since the shoulders 57 are rounded with this embodiment, this embodimentprovide advantages same as those of Embodiment 4.

(Embodiment 6)

FIGS. 37(a) through 37(f) are schematic cross sectional views of asemiconductor device showing steps of still another embodiment(Embodiment 6) of manufacturing method according to the invention. Notethat only part of the semiconductor device corresponding to the fifthwiring layer of Embodiment 1 is shown in FIGS. 37(a) through 37(e). Morespecifically, only some of the wires and the underlying interlayerconnecting wires of the semiconductor device are shown in a simplifiedfashion.

This embodiment differs from Embodiment 1 in that the insulating film 36operating as an intermediary stopper layer of Embodiment 1 is not usedwith this embodiment.

Referring firstly to FIG. 37(a), insulating films 34, 35 and 38 areformed sequentially on the lower wiring layer 33. Typically, theinsulating films 34, 38 may be made of silicon nitride whereas theinsulating film 35 may be made of silicon oxide as in Embodiment 1.However, since the insulating film 35 operates also as the insulatingfilm 37 of Embodiment 1, it is made as thick as 850 to 900 nm. Then, asin Embodiment 1, the groove pattern 40 is transferred into theinsulating film 38 by using resist film 39.

Then, as shown in FIG. 37(b), an anti-reflection film 41 is formed tofill the grooves 40 of the insulating film 38 as in Embodiment 1 and aresist film 42 having openings 43 for forming contact holes is formed ashole pattern also as in the case of Embodiment 1.

Thereafter, as shown in FIG. 37(c), the hole pattern 43 is transferredinto the insulating film 35 by using the resist film 42 as mask. As inEmbodiment 1, the transfer operation is conducted under conditions goodfor etching silicon oxide film to form contact holes 43 in theinsulating film 35 as deep as 500 nm. The depth of the contact holes 43can be controlled by controlling the duration of the etching operation.

Then, as shown in FIG. 37(d), the resist film 42 and the anti-reflectionfilm 41 are removed by using a technique similar to the one used inEmbodiment 1.

Thereafter, as shown in FIG. 37(e), the groove pattern 40 carried by theinsulating film 38 is transferred into the insulating film 35 by usingthe insulating film 38 as mask under conditions good for etching siliconoxide film as described above in terms of Embodiment 1. The grooves 40are made as deep as 400 nm. The depth of the grooves 40 can becontrolled by controlling the duration of the etching operation.

Since the contact holes 43 are already formed in the insulating film 35,the bottoms of the contact holes are also etched by this etchingoperation so that the bottoms of the contact holes 43 get to the lowersurface of the insulating film 34 when the grooves 40 are formed as deepas 400 nm by the etching operation.

Then, as shown in FIG. 37(f), the insulating film 38 and the insulatingfilm 34 left on the bottoms of the contact holes 43 are removed tocomplete the operation of forming the wiring grooves 44 and the contactholes 45. This removing operation is an etching operation conductedunder conditions good for etching silicon nitride film. All thesubsequent steps of this embodiment are same as those of Embodiment 1.

This embodiment provides an advantage that no silicon nitride filmshowing a high dielectric constant is formed on the bottoms of thewiring grooves because, unlike Embodiment 1, the insulating film 36 thatis a silicon nitride film operating as intermediary stopper is not usedin this embodiment. As a result, the inter-wire capacitance is reducedto improve the performance of the semiconductor device.

(Embodiment 7)

FIGS. 38(a) through 38(f) are schematic cross sectional views of asemiconductor device showing steps of still another embodiment(Embodiment 7) of manufacturing method according to the invention. Notethat only part of the semiconductor device corresponding to the fifthwiring layer of Embodiment 1 is shown in FIGS. 38(a) through 38(f). Morespecifically, only some of the wires and the underlying interlayerconnecting wires of the semiconductor device are shown in a simplifiedfashion.

This embodiment differs from Embodiment 1 in that the insulating film 36operating as an intermediary stopper layer of Embodiment 1 is not usedwith this embodiment and a marker layer 58 is additionally provided inorder to form the wiring grooves and the contact holes.

Referring firstly to FIG. 38(a), insulating films 34, 35, a marker layer58 and insulating films 37, 38 are formed sequentially on the lowerwiring layer 33. The insulating films 34, 35, 37 and 38 are same asthose of Embodiment 1. The marker layer 58 may be made of siliconnitride, PSG (phosphor-silicate-glass) or BPSG(boron-phosphor-silicate-glass) and have a film thickness between 10 and50 nm. As described hereinafter, such a marker layer 58 may be used asmarker for etching operations. The insulating films 35, 37 are made toshow a total film thickness of about 850 nm and the marker layer 58 isformed to define the bottom of the contact holes in the next step. Forexample, it may be located 500 nm below the upper surface of theinsulating film 37. In other words, the insulating films 35 and 37 maybe made to show respective heights of 350 nm and 500 nm (if the filmthickness of the marker layer is negligible).

Then, the groove pattern 40 is transferred into the insulating film 38by using a resist film 39 as in Embodiment 1.

Thereafter, as shown in FIG. 38(b), an anti-reflection film 41 is formedto fill the grooves 40 of the insulating film 38 as in Embodiment 1 anda resist film 42 having openings 43 for forming contact holes is formedas hole pattern also as in the case of Embodiment 1.

Then, as shown in FIG. 38(c), the hole pattern 43 is transferred intothe insulating film 35 by using the resist film 42 as mask. As inEmbodiment 1, the transfer operation is conducted under conditions goodfor etching silicon oxide film to form contact holes 43 in theinsulating film 35. The depth of the contact holes 43 can be controlledby detecting the marker layer 58. More specifically, since the markerlayer 58 contains nitrogen (N), boron (B) and phosphor (P) along withother elements, the depth of the contact holes 43 can be controlled bymeans of plasma spectroscopy of detecting the emission of light of theplasma of nitrogen, boron and phosphor produced by the etchingoperation. The etching operation is terminated when the emission oflight is detected so that the contact holes 43 may show the intendedheight. With this technique, the depth of the contact holes can becontrolled with ease.

Then, as shown in FIG. 38(d), the resist film 42 and the anti-reflectionfilm 41 are removed by using a technique similar to the one used inEmbodiment 1.

Thereafter, as shown in FIG. 38(e), the groove pattern 40 carried by theinsulating film 38 is transferred into the insulating film 35 by usingthe insulating film 38 as mask under conditions good for etching siliconoxide film as described above in terms of Embodiment 1. The grooves 40are made as deep as 400 nm. The depth of the grooves 40 can becontrolled by controlling the duration of the etching operation. Sincethe contact holes are already formed in the insulating film 35, thebottoms of the contact holes are also etched by this etching operationso that the bottoms of the contact holes 43 get to the lower surface ofthe insulating film 34 when the grooves 40 are formed as deep as 400 nmby the etching operation as in the case of Embodiment 6.

Then, as shown in FIG. 38(f), the insulating film 38 and the insulatingfilm 34 left on the bottoms of the contact holes 43 are removed tocomplete the operation of forming the wiring grooves 44 and the contactholes 45. This removing operation is an etching operation conductedunder conditions good for etching silicon nitride film. All thesubsequent steps of this embodiment are same as those of Embodiment 1.

This embodiment provides an advantage that no silicon nitride filmshowing a high dielectric constant is formed on the bottoms of thewiring grooves because, unlike Embodiment 1, the insulating film 36 thatis a silicon nitride film operating as intermediary stopper is not usedin this embodiment. As a result, the inter-wire capacitance is reducedto improve the performance of the semiconductor device. This embodimentprovides an additional advantage that the depth of the contact holes 43can be controlled with ease.

Note that a semiconductor device formed by this embodiment ofmanufacturing method comprises a marker layer below the bottom of thewiring layers.

(Embodiment 8)

FIGS. 39(a) through 39(f) are schematic cross sectional views of asemiconductor device showing steps of still another embodiment(Embodiment 8) of manufacturing method according to the invention. Notethat only part of the semiconductor device corresponding to the fifthwiring layer of Embodiment 1 is shown in FIGS. 39(a) through 39(f). Morespecifically, only some of the wires and the underlying interlayerconnecting wires of the semiconductor device are shown in a simplifiedfashion.

Referring firstly to FIG. 39(a), insulating films 34 through 37, amarker layer 58 and insulating films 37′, 38 are formed sequentially onthe lower wiring layer 33. The insulating films 34, 36, and 38 aretypically made of silicon nitride, whereas the insulating films 35, 37and 37′ are typically made of silicon oxide just like the correspondinginsulating films of Embodiment 1. The marker layer 58 is same as that ofEmbodiment 7.

The insulating films 37, 37′ are made to show a total film thickness ofabout 450 nm and the marker layer 58 is formed 400 nm above the uppersurface of the insulating film 37′. In other words, the insulating film37′ may be made to show a film thickness of 50 nm (if the film thicknessof the marker layer is negligible).

Then, the groove pattern 40 is transferred into the insulating film 38by using a resist film 39 as in Embodiment 1.

Thereafter, as shown in FIG. 39(b), an anti-reflection film 41 is formedto fill the grooves 40 of the insulating film 38 as in Embodiment 1 anda resist film 42 having openings 43 for forming contact holes is formedas hole pattern also as in the case of Embodiment 1.

Then, as shown in FIG. 39(c), the hole pattern 43 is transferred intothe insulating film 35 by using the resist film 42 as mask. As inEmbodiment 1, the transfer operation is conducted under conditions wheresilicon oxide film is etched with each but silicon nitride film ishardly etched. In other words, the insulating film 36 that is a siliconnitride film is used as etching stopper. With this technique, the depthof the contact holes can be controlled with ease. Then, the insulatingfilm 36 left on the bottoms of the contact holes 43 is removed byetching.

Then, as shown in FIG. 39(d), the resist film 42 and the anti-reflectionfilm 41 are removed by using a technique similar to the one used inEmbodiment 1.

Thereafter, as shown in FIG. 39(e), the groove pattern 40 carried by theinsulating film 38 is transferred into the insulating film 37′ by usingthe insulating film 38 as mask under conditions good for etching siliconoxide film as described above in terms of Embodiment 1. The depth of thewiring grooves 40 can be controlled by detecting the marker layer 58.More specifically, since the marker layer 58 contains nitrogen (N),boron (B) and phosphor (P) along with other elements, the depth of thecontact holes 43 can be controlled by means of plasma spectroscopy ofdetecting the emission of light of the plasma of nitrogen, boron andphosphor produced by the etching operation. The etching operation isterminated when the emission of light is detected so that the wiringgrooves 40 may show the intended height. With this technique, the depthof the wiring grooves 40 can be controlled with ease. The grooves 40 aremade as deep as 400 nm in a well-controlled manner because the depth isdefined by the marker layer 58. Since the contact holes are alreadyformed in the insulating film 35 at the time of this etching operation,the bottoms of the contact holes are also etched by this etchingoperation so that the bottoms of the contact holes 43 get to the lowersurface of the insulating film 34 as in the case of Embodiment 6. Itwill be appreciated that no problem arises if the bottoms of the contactholes 43 are excessively etched because the insulating film 34 that is asilicon nitride film is formed thereunder.

Then, as shown in FIG. 38(f), the insulating film 38 and the insulatingfilm 34 left on the bottoms of the contact holes 43 are removed tocomplete the operation of forming the wiring grooves 44 and the contactholes 45. This removing operation is an etching operation conductedunder conditions good for etching silicon nitride film. All thesubsequent steps of this embodiment are same as those of Embodiment 1.

This embodiment provides an advantage that, although an intermediarylayer of silicon nitride showing a high dielectric constant is used, itdoes not significantly increase the inter-wire capacitance because thesilicon nitride film is formed below the bottoms of the wiring grooves.In other words, the silicon nitride film (insulating film 36) is held incontact with the interlayer connecting wires for connecting the upperwire and the lower wires, which are not found everywhere in the wireforming regions. More specifically, since the interlayer connectingwires are formed only in part of the wire forming regions, the overallcapacitance produced by the interlayer connecting wires and theinsulating film 36 is not large. On the other hand, the depth of thecontact holes and that of the wiring grooves can be controlled with easein this embodiment. In other words, both the wiring grooves and thecontact holes can be formed in a highly accurate manner. The highaccuracy of forming the depth of the wiring grooves and that of thecontact holes allows the use of thin insulating films (insulating films34, 36) operating as stoppers to consequently reduce the inter-wirecapacitance and hence improve the performance of the semiconductordevice.

(Embodiment 9)

FIGS. 40(a) through 40(f) are schematic cross sectional views of asemiconductor device showing steps of still another embodiment(Embodiment 9) of manufacturing method according to the invention. Notethat only part of the semiconductor device corresponding to the fifthwiring layer of Embodiment 1 is shown in FIGS. 40(a) through 40(f). Morespecifically, only some of the wires and the underlying interlayerconnecting wires of the semiconductor device are shown in a simplifiedfashion.

This embodiment differs from Embodiment 8 in that the insulating film 36is not used in this embodiment.

Referring firstly to FIG. 40(a), insulating films 34, 35, a marker layer58 and insulating films 35′, 38 are formed sequentially on the lowerwiring layer 33. The insulating films 34 and 38 are typically made ofsilicon nitride, whereas the insulating films 35 and 35′ are typicallymade of silicon oxide just like the corresponding insulating films ofEmbodiment 1. The marker layer 58 is same as that of Embodiment 7.

The insulating films 35, 35′ are made to show a total film thickness ofabout 850 nm and the marker layer 58 is formed 400 nm above the uppersurface of the insulating film 35′. In other words, the insulating film35 may be made to show a film thickness of 450 nm if the film thicknessof the marker layer is negligible.

Then, the groove pattern 40 is transferred into the insulating film 38by using a resist film 39 as in Embodiment 1.

Thereafter, as shown in FIG. 40(b), an anti-reflection film 41 is formedto fill the grooves 40 of the insulating film 38 as in Embodiment 1 anda resist film 42 having openings 43 for forming contact holes is formedas hole pattern also as in the case of Embodiment 1.

Then, as shown in FIG. 40(c), the hole pattern 43 is transferred intothe insulating films 35, 35′ by using the resist film 42 as mask Thetransfer operation is conducted under conditions good for etchingsilicon oxide film. The depth of the contact holes 43 can be controlledby controlling the duration of the etching operation the contact holes43 are made as deep as 500 nm. While the contact holes 43 are cutthrough the marker layer 58 by the etching operation, the emission oflight of the plasma produced by the marker layer will be neglected.

Then, as shown in FIG. 40(d), the resist film 42 and the anti-reflectionfilm 41 are removed by using a technique similar to the one used inEmbodiment 1.

Thereafter, as shown in FIG. 40(e), the groove pattern 40 carried by theinsulating film 38 is transferred into the insulating film 35′ by usingthe insulating film 38 as mask under conditions good for etching siliconoxide film as in the case of Embodiment 1. The depth of the wiringgrooves 40 can be controlled by detecting the marker layer 58 as in thecase of Embodiment 8. More specifically, since the marker layer 58contains nitrogen (N), boron (B) and phosphor (P) along with otherelements, the depth of the contact holes 43 can be controlled by meansof plasma spectroscopy of detecting the emission of light of the plasmaof nitrogen, boron and phosphor produced by the etching operation. Theetching operation is terminated when the emission of light is detectedso that the wiring grooves 40 may show the intended height. With thistechnique, the depth of the wiring grooves 40 can be controlled withease. Since the contact holes are already formed in the insulating film35 at the time of this etching operation, the bottoms of the contactholes are also etched by this etching operation so that the bottoms ofthe contact holes 43 get to the lower surface of the insulating film 34as in the case of Embodiment 6. It will be appreciated that no problemarises if the bottoms of the contact holes 43 are excessively etchedbecause the insulating film 34 that is a silicon nitride film is formedthereunder.

Then, as shown in FIG. 40(f), the insulating film 38 and the insulatingfilm 34 left on the bottoms of the contact holes 43 are removed tocomplete the operation of forming the wiring grooves 44 and the contactholes 45. This removing operation is an etching operation conductedunder conditions good for etching silicon nitride film. All thesubsequent steps of this embodiment are same as those of Embodiment 1.

This embodiment provides an advantage that no silicon nitride filmshowing a high dielectric constant is formed on the bottoms of thewiring grooves because the insulating film 36 that is a silicon nitridefilm operating as intermediary stopper is not used in this embodiment.As a result, the inter-wire capacitance is reduced to improve theperformance of the semiconductor device. On the other hand, the wiringgrooves 44 can be formed in a well-controlled fashion by using themarker layer 58.

(Embodiment 10)

FIGS. 41(a) through 41(f) are schematic cross sectional views of asemiconductor device showing steps of still another embodiment(Embodiment 10) of manufacturing method according to the invention. Notethat only part of the semiconductor device corresponding to the fifthwiring layer of Embodiment 1 is shown in FIGS. 41(a) through 41(f). Morespecifically, only some of the wires and the underlying interlayerconnecting wires of the semiconductor device are shown in a simplifiedfashion.

Referring firstly to FIG. 41(a), insulating films 34, 50 and 59′ areformed sequentially on the lower wiring layer 33. The insulating films34 and 38 are typically made of silicon nitride, whereas the insulatingfilms 59 and 59′ are typically made of silicon oxide. Then, contactholes are formed in the insulating film 59 and interlayer connectingwires are formed in the respective contact holes. In other words, theinsulating film 59 operates as interlayer insulating film. Wiringgrooves are formed in the insulating film 59′ and wires are formed inthe respective wiring grooves. In other words, the insulating film 59operates as inter-wire insulating film.

The insulating film 59 may be made of TEOS oxide and the insulating film59′ may be made of a material showing an etching selectivity relative tothe TEOS oxide film. Materials that can be used for the insulating film59′ typically include SOG (spin on glass). As a result of using amaterial showing an etching selectivity relative to the insulating film59 for the insulating film 59′, the insulating film 59 can be used asetching stopper when transferring the groove pattern into the insulatingfilm 59′. More specifically, materials that can be used for theinsulating film 59′ include organic SOG, fluorine-containing SOG andother materials showing a low dielectric constant. As a result of usinga low dielectric constant material for the inter-wire insulating film(insulating film 59′), the inter-wire capacitance of the wires of thelayer can be reduced. On the other hand, the inter-wire capacitancebetween the wiring layers can be reduced by increasing the filmthickness of the insulating film 59. Typically, the insulating film 59may have a film thickness of 450 nm, whereas the insulating film 59′ mayhave a film thickness of 400 nm.

Then, the groove pattern 40 is transferred into the insulating film 38by using a resist film 39 as in Embodiment 1.

Thereafter, as shown in FIG. 41(b), an anti-reflection film 41 is formedto fill the grooves 40 of the insulating film 38 as in Embodiment 1 anda resist film 42 having openings 43 for forming contact holes is formedas hole pattern also as in the case of Embodiment 1.

Then, as shown in FIG. 41(c), the hole pattern 43 is transferred intothe insulating films 59, 59′ by using the resist film 42 as mask. Thetransfer operation includes the first etching step using a mixture gasof CH₃ and C₄F₈ and the second etching step using C₄F₈ gas. The firstetching step is conducted under conditions where SOG is easily etchedbut TEOS oxide film is hardly etched so that the etching is stopped onthe upper surface of the insulating film 59 (TEOS oxide film). In otherwords, the insulating film 59 is used as etching stopper in the firstetching step. As a result, the etching depth can be uniformed to anenhanced degree. On the other hand, the second etching step is conductedunder conditions good for etching TEOS oxide film so that the holepattern 43 can be transferred also into the insulating film 59. Theetching depth of the second etching step is about 50 nm.

Then, as shown in FIG. 41(d), the resist film 42 and the anti-reflectionfilm 41 are removed by using a technique similar to the one used inEmbodiment 1.

Thereafter, as shown in FIG. 41(e), the groove pattern 40 carried by theinsulating film 38 is transferred into the insulating film 59′ by usingthe insulating film 38 carrying the groove pattern 40 as mask underconditions good for etching both SOG and TEOS oxide film (both theinsulating films 59 and 591) (by using a mixture gas containing C₄F₈).As a result, the groove pattern 40 is transferred into the insulatingfilm 59′ and, at the same time, the hole pattern 40 is transferredfurther deep into the insulating film 59. The depth of the wiringgrooves 40 can be controlled by controlling the duration of the etchingoperation. It will be appreciated that no problem arises if the bottomsof the contact holes 43 are excessively etched because the insulatingfilm 34 that is a silicon nitride film is formed thereunder. On theother hand, it is necessary that the bottoms of the contact holes 43 getto the upper surface of the insulating film 34 by the time when thebottoms of the wiring grooves 40 get to the upper surface of theinsulating film 59. Therefore, the difference between the rate ofetching the insulating film 59′ (SOG) and that of etching the insulatingfilm 59 (TEOS oxide film) in the step of FIG. 41(e) is reflected to thedepth of the contact holes 43 in the step of FIG. 41(c). Thus, the depthof the contact holes 43 can be regulated in the second etching step.

Then, as shown in FIG. 41(f), the insulating film 38 and the insulatingfilm 34 left on the bottoms of the contact holes 43 are removed tocomplete the operation of forming the wiring grooves 44 and the contactholes 45. This removing operation is an etching operation conductedunder conditions good for etching silicon nitride film. All thesubsequent steps of this embodiment are same as those of Embodiment 1.

This embodiment provides an advantage that no silicon nitride filmshowing a high dielectric constant is formed on the bottoms of thewiring grooves because the insulating film 36 that is a silicon nitridefilm operating as intermediary stopper is not used in this embodiment.As a result, the inter-wire capacitance is reduced to improve theperformance of the semiconductor device. Additionally, the depth of thecontact holes 43 and that of the wiring grooves 40 can be controlled ina well-controlled fashion by utilizing the difference in the rate ofetching the insulating film 59 and that of etching the insulating film59′. Still additionally, the inter-wire capacitance of the semiconductordevice can be reduced to improve the performance of the device by usinga low dielectric constant material (organic SOG, fluorine-containingSOG) for the inter-wire insulating film (insulating film 59′).

It may be needless to say that the insulating film 59 may be made of alow dielectric constant material such as organic SOG orfluorine-containing SOG if the insulating film 59′ is made of TEOS oxidefilm.

(Embodiment 11)

FIGS. 42(a) through 42(f) are schematic cross sectional views of asemiconductor device showing steps of still another embodiment(Embodiment 10) of manufacturing method according to the invention. Notethat only part of the semiconductor device corresponding to the fifthwiring layer of Embodiment 1 is shown in FIGS. 42(a) through 42(f). Morespecifically, only some of the wires and the underlying interlayerconnecting wires of the semiconductor device are shown in a simplifiedfashion.

Firstly, as shown in FIG. 42(a), insulating films 34 through 37, a hardmask layer 60 and a transfer mask layer 61 are sequentially formed onthe lower wiring layer 33. The insulating films 34 through 37 are sameas those of Embodiment 1. The hard mask layer 60 is a metal layertypically made of tungsten. The transfer mask layer 61 may be made ofTEOS oxide film. The hard mask layer 60 and the transfer mask layer 61may have respective film thickness of 200 nm and 100 nm. The hard-masklayer 60 may be formed by sputtering or CVD.

The transfer mask layer 61 and the hard mask layer 60 operate astransfer mask when transferring the groove pattern 40 just like theinsulating film 38 of Embodiment 1. From the viewpoint of preventing thedrooping of the pattern along the edges thereof, the transfer maskpreferably has a large film thickness. However, if the transfer mask istoo thick, the wiring grooves may not be satisfactorily filled with theanti-reflection film to consequently produce steps when forming a resistfilm carrying openings for the contact holes. Such steps obviouslyreduce the accuracy of forming contact holes. However, the combined useof a transfer mask layer 61 and a hard mask layer 60 of this embodimentcan effectively prevent the possible dropping of the pattern along theedges thereof and, at the same time, reduce the steps of the transfermask.

Then, as in Embodiment 1, a resist film 39 carrying a groove pattern 40is formed and the groove pattern 40 of the resist film 39 is transferredinto the transfer mask layer 61.

Then, as shown in FIG. 42(b), an anti-reflection film 41 is formed tofill the grooves 40 of the transfer mask layer 61 as in Embodiment 1 andsubsequently a resist film 42 having a hole pattern 43 is formed also asin Embodiment 1. In this stage of operation, the steps of the transfermask layer 61 is 100 nm high at most so that they can be filledsatisfactorily by the anti-reflection film 41.

Thereafter, as shown in FIG. 42(c), the hole pattern 43 is transferredinto the hard mask layer 60, the insulating films 37, 37 and part of theinsulating film 35 by using the resist film 42 as mask. The depth of thecontact holes 43 is controlled by controlling the duration of theetching operation.

Then, as shown in FIG. 42(d), the resist film 42 and the anti-reflectionfilm 41 are removed as in Embodiment 1. Then, the groove pattern 40 istransferred into the hard mask layer 60 by using the transfer mask layer61 as mask under conditions good for selectively etching tungsten.

Subsequently, as shown in FIG. 42(e), the groove pattern 40 istransferred into the insulating film 37 by using the transfer mask layer61 carrying the groove pattern 40 and the hard mask layer 60 as mask.This transfer operation is an etching operation conducted underconditions good for etching silicon oxide film. Although the transfermask layer 61 is removed by the etching operation, the groove pattern 40is accurately transferred because of the presence of the hard mask layer60. The etching conditions of this operation are same as those ofEmbodiment 1. The depth of the wiring grooves 40 can be controlled byusing the insulating film 36 as etching stopper. Since the contact holes43 are made to run through the insulating 36 and formed partly in theinsulating film prior to the etching operation, the bottoms of thecontact holes 43 get to the insulating film 34 as described above byreferring to Embodiment 1.

Then, as shown in FIG. 42(f), the insulating film 38 left on the bottomsof the wiring grooves 40 and the insulating film 34 left on the bottomsof the contact holes 43 are removed to complete the operation of formingthe wiring grooves 44 and the contact holes 45. This removing operationis an etching operation conducted under conditions good for etchingsilicon nitride film. All the subsequent steps of this embodiment aresame as those of Embodiment 1.

Note that, in this embodiment, the hard mask layer 60 is not removed inthis stage of operation and left on the insulating film 37. Since thehard mask layer 60 is made of metal film, it can reduce the resistanceof the surface of the substrate in the step of forming the plating layerfor wires so as to facilitate the operation of forming the platinglayer. It may be needless to say that the hard mask layer 60 is removedduring the CMP process for forming the wires.

This embodiment provides an advantage of improving the accuracy offorming wiring grooves because they are formed by using a hard masklayer 60. On the other hand, the resist film 42 carrying the holepattern 43 can be formed highly accurately because the transfer of thegroove pattern 40 into the hard mask layer 60 is realized by using atransfer mask layer 61.

It will be appreciated that the hard mask layer 60 may be formed afterforming the transfer mask layer 61. In other words, it is important tocombine the hard mask layer 60 and the transfer mask layer 61 in orderto make them operate as mask when transferring the groove pattern 40into the insulating film 37 and the sequent of forming them is notimportant.

(Embodiment 12)

FIGS. 43(a) through 43(f) are schematic cross sectional views of asemiconductor device showing steps of still another embodiment(Embodiment 10) of manufacturing method according to the invention. Notethat only part of the semiconductor device corresponding to the fifthwiring layer of Embodiment 1 is shown in FIGS. 43(a) through 43(f). Morespecifically, only some of the wires and the underlying interlayerconnecting wires of the semiconductor device are shown in a simplifiedfashion.

Firstly, as shown in FIG. 43(a), insulating films 34 and 35 aresequentially formed on the lower wiring layer 33. The insulating films34 and 35 are same as those of Embodiment 6. Then, a resist film 62 isformed on the insulating film 35 and a groove pattern 40 is formed inthe resist pattern 62. Thus, no film corresponding to the insulatingfilm 38 of the preceding embodiments is formed in this embodiment andthe resist film is directly utilized for the groove pattern. The resistfilm 62 may typically be made of photosensitive polyimide. As a resultof using photosensitive polyamide for the resist film 62, it can be madeto show an etching selectivity relative to the resist film formed forthe hole pattern, which will be described below in terms of the nextmanufacturing step.

Then, as shown in FIG. 43(b), a resist film 63 carrying a hole pattern43 is formed on the resist film 62. The resist film 63 is an ordinaryresist film (e.g., Novolac type photoresist film).

Then, as shown in FIG. 43(c), the hole pattern 43 is transferred intothe insulating film 35 by using the resist film 63 as mask. The holesformed in the insulating film 35 are made to show a depth of 500 nm. Thedepth of the holes 43 can be controlled by controlling the duration ofthe etching operation.

Thereafter, as shown in FIG. 43(d), the resist film 63 is removedtypically by means of an oxygen plasma ashing technique. Since polyimidetype resist film has an anti-ashing effect, the resist film 62 is leftunremoved so that it is possible to remove only the resist film 63.

Then, as shown in FIG. 43(e), the groove pattern 40 is transferred intothe insulating film 35 by using the resist film 62 carrying the groovepattern 40 as mask under conditions good for etching silicon oxide film.The etching conditions are same as those of Embodiment 1. The groovesformed in the insulating film 35 are made to show a depth of 400 nm. Thedepth of the grooves 40 can be controlled by controlling the duration ofthe etching operation.

Since the hole pattern 43 has already been transferred into theinsulating film 35 at the time of forming the grooves by etching, theholes 43 in the insulating film 35 are also etched at the bottomsthereof so that, when the grooves 40 are formed as deep as 400 nm, thebottoms of the holes 43 get to the insulating film 34 as described aboveby referring to Embodiment 6.

Subsequently, as shown in FIG. 43(f), the resist film 62 is removedtypically by means of a wet etching technique using butyl acetate assolvent. Then, the insulating film 34 is removed from the bottoms of theholes 43. The operation of forming the wiring grooves 44 and the contactholes 45 is completed at this stage. The insulating films 34 is removedfrom the bottoms of the holes 43 under conditions good for etchingsilicon nitride film. All the subsequent steps of this embodiment aresame as those of Embodiment 1.

(Embodiment 13)

FIG. 44(a) is are schematic cross sectional views of a semiconductordevice showing steps of exposing the resist film 42 for forming a holepattern 43 to light in Embodiment 1 in the process of manufacturing thesemiconductor device.

After forming the resist film 42 by applying resist as shown in FIG. 11illustrating Embodiment 1, the hole pattern 43 is formed there by meansof photolithography as shown in FIG. 12. FIG. 44(a) illustrates thisstep in greater detail.

Referring now to FIG. 44(a), markers 62 are formed in the fourth wiringlayer along with the wires 33. A mask 65 carrying the hole pattern isformed on the resist film 42. Note that the mask 65 also carries markers66 along with the hole pattern 43.

Then, the resist film 42 is exposed to light, by using the mask. Themask 65 is aligned by referring to the markers 64 of the fourth wiringlayer (of the lower wires). More specifically, the markers 64 of thefourth wiring layer and the corresponding markers 66 of the mask 65 arealigned and light is irradiated from above the mask 65 to expose theresist film 42 to light. The areas 67 exposed to light are removed in asubsequent chemical processing step to produce holes 43 as shown in FIG.12.

With this technique, the hole pattern 43 can be aligned in simple andaccurate manner. More specifically, as described above by referring toEmbodiment 1, the groove pattern 40 is formed in the insulating film 38.However, it is difficult to align the mask if the hole pattern 43 isformed by referring to the groove pattern 40. In other words, since theinsulating film 38 has a thickness as small as 100 nm and hence is verythin and generally transparent to visible light, any markers formed inthe insulating film 38 can hardly be detected. If detected, it is highlydifficult to read the markers of the insulating film 38 so that the mask65 and the markers can hardly be aligned. On the other hand, the markers64 of the wires are made of metal and can be read with ease by means ofa mask aligner so that the mask and the markers can be alignedaccurately. Additionally, the mutual displacement of the lower wires andthe contact holes 45 can be minimized to realize a reliable contactbetween the upper and lower wires when the hole pattern 43 is formed byreferring to the markers 64 of the lower wires. Meanwhile, although thegroove pattern 40 is formed by referring to the markers 64 of the lowerwires, no specific problems arise if the mask is displaced relative tothe hole pattern 43 as discussed earlier. Thus, in the embodiment, thehole pattern 43 can be aligned easily and accurately in a manner asdescribed above.

Alternatively, as shown in FIG. 44(b), markers 68 may also be formed inthe insulating film 38 so that each of the markers 68 and thecorresponding one of the markers 64 may be aligned with thecorresponding one of the markers 66 of the mask 65 arranged at themiddle thereof as viewed from above. This alignment operation is alsoeasy and can minimize the error in reading the markers 68 of theinsulating film 38.

(Embodiment 14)

FIG. 45(a) is a schematic plan view of a semiconductor device formed byEmbodiment 14 of the invention and FIGS. 45(b 1), 45(c 1) through 45(b3), 45(c 3) are schematic cross sectional views of the semiconductordevice of FIG. 45(a). This embodiment will be described in terms of thehole pattern 43 that is similar to that of Embodiment 2 but the diameterof the holes of the hole pattern 43 is made greater than the width ofthe grooves of the groove pattern 40 as observed in a direction(y-direction) perpendicular to the direction of the wiring grooves(x-direction). As seen from the plan view of FIG. 45(a), the illustratedhole of the hole pattern 43 has a diameter Ly in the y-direction greaterthan the width Lw of the wiring grooves (formed by the groove pattern40). The diameter Ly of the hole in the y-direction may be made equal tothe width of the grooves plus alignment tolerance. Then, with themanufacturing method of Embodiment 2, the edges of the holes of the holepattern 43 formed in the y-direction by etching are defined by thegroove p-type 40. In other words, they are formed in a self-aligningmanner relative to the groove pattern 40 so that the diameter of theholes of hole pattern 43 in the y-direction would never become smallerthat the width Lw of the openings of the groove pattern 40. On the otherhand, the diameter of the holes of the hole pattern 43 in thex-direction is defined by the groove pattern 40 so that it would neverbecome greater than the width Lateral wall of the openings of the groovepattern 40. As a result, the area of the cross section (Lw×Lx) of theinterlayer connecting wires 50 can be secured, while their resistancecan be reduced and the intervals of the wires can be minimized toimprove the performance, the degree of integration and the reliabilityof the semiconductor device.

Now, this embodiment will be described by referring to the crosssectional views of FIGS. 45(b), 45(c 1) through 45(b 3), 45(c 3). Notethat FIGS. 45(b 1) through 45(b 3) are cross sectional views takena-long line B—B′ in FIG. 45(a), whereas FIGS. 45(c 1) through 45(c 3)are cross sectional views taken along line C—C′ in FIG. 45(a).

Firstly, as shown in FIGS. 45(b 1), 45(c 1), insulating films 34, 35 and38 are sequentially formed on the lower wires 33 as in Embodiment 6 andthe groove pattern 40 is transferred into the insulating film 38 as inEmbodiment 1. Thereafter, an anti-reflection film 41 is formed to fillthe grooves formed in the insulating film 38 by using the groove pattern40 as in Embodiment 1 and then a resist film 42 carrying the holepattern 43 is formed also as in Embodiment 1. Note that, the holes 43have a diameter greater than the width of the grooves formed by thegroove pattern 0 in the direction along line C—C′ (y-direction) as seenfrom FIG. 45(c 1).

Then, as shown in FIGS. 45(b 2), 45(c 2), the hole pattern 43 istransferred into the insulating film 35 by using the resist film 42 asmask. The transfer is realized by means of an etching operationconducted under conditions where silicon oxide film is etched butsilicon nitride film is hardly etched as described above by referring toEmbodiment 2. Thus, as shown in FIG. 45(c 2), the holes are formed in aself-aligning fashion relative to the grooves in the y-direction and theinsulating film 38 is only partly etched below the holes of the resistfilm 42 and the insulating film 35 located under the insulating film 38is left unetched.

The holes 43 are formed as deep as 500 nm in the insulating film 35. Thedepth of the holes can be controlled by controlling the duration of theetching operation.

Then, the resist film 42 and the anti-reflection film 41 are removed bymeans of a method same as the one described above by referring toEmbodiment 1.

Then, as shown in FIGS. 45(b 3), 45(c 3), the insulating film 35 isetched by using the insulating film 38 (the groove pattern 40) as mask.As a result, the groove pattern 40 is transferred into the insulatingfilm 35. The transfer is realized under conditions good for etchingsilicon oxide film as in Embodiment 1. Thus, the diameter Lw of thecontact holes 45 can be made substantially equal to the width Lw of thewires 44. The grooves 40 are made as deep as 400 nm. The dept of thegrooves can be controlled by controlling the duration of the etchingoperation. Since the hole pattern 43 has already been transferred intothe insulating film 35 at the time of forming the grooves by etching,the holes 43 in the insulating film 35 are also etched at the bottomsthereof so that, when the grooves 40 are formed as deep as 400 nm, thebottoms of the holes 43 get to the insulating film 34 as described aboveby referring to Embodiment 1. All the subsequent steps of thisembodiment are same as those of Embodiment 1. As a result, the wires 44and the contact holes 45 are formed and then the wires 49 (theinterlayer connecting wires 50) are formed as in Embodiment.

With this embodiment of manufacturing method according to the invention,the holes are formed in a self-aligning manner relative to theinsulating film 38 (the groove pattern 40) so that any relativemisalignment of the mask of the hole pattern 43 and that of the groovepattern 40 can be harmless in the y-direction. Additionally, thedisplacement, if any, in the y-direction does not make the contact holesdefective and they are made to show the designed diameter Lw (crosssectional area). In other words, the diameter of the contact holes 45 ismade substantially equal to the width Lw of the wires 44. As a result,the resistance of the wires 49 can be reduced to improve the reliabilityof the interlayer connecting wires and hence the performance and thereliability of the semiconductor device. Additionally, if the diameterLy of the contact holes 43 formed in the insulating film 35 in they-direction is made greater than the width Lw of the wiring grooves, itdoes not exceed the value defined by the width Lw. Therefore, theintervals separating the wires can be minimized to raise the wiredensity and improve the degree of integration of the semiconductordevice.

FIG. 46(a) is a schematic plan view of wires 49 a formed by thisembodiment. FIG. 46(b) is a cross sectional view of a wire 49 takenalong line G-H in FIG. 46(a). As shown, contact holes are formed inareas where the openings of the pattern of the wires and those of thehole pattern 43 overlap each other (hatched area). The produced contactholes shows a diameter same as the width W of the wires 49 a so that theresistance of the contact holes can be minimized.

While the invention of the inventors is described above in terms ofspecific embodiments, the present invention is by no means limitedthereto and the embodiments may be modified in various different wayswithout departing from the scope of the invention.

For instance, any of the above described embodiments may be combinedwithout departing from the scope of the invention, More specifically,the process of rounding the shoulders as described above by referring toEmbodiments 4 and 5 may also be applied to the remaining embodimentsexcept Embodiment 11.

While the insulating film 38 is made of silicon nitride film in all theapplicable embodiments, it may be made of some other material providedthat it shows an etching selectivity relative to the underlying siliconoxide film. Materials that can be used for the insulating film 38include tungsten, titanium nitride (TiN), aluminum (Al), tantalum (Ta)and molybdenum (Mo) as well as nitrides thereof.

Some of the advantages of the present invention will be listed below.

Firstly, fine dual damascene grooves can be formed without leaving anyforeign object in the contact holes to consequently improve thereliability of the connection of wires and hence the performance of thesemiconductor device.

Secondly, Sufficient space can be provided when forming contact holes sothat the resistance of connecting the wiring layers can be significantlyreduced to consequently improve the performance of the semiconductordevice.

Thirdly, the inter-wire capacitance can be reduced to improve theperformance of the semiconductor device.

What is claimed is:
 1. A method of manufacturing a semiconductor device,comprising steps of: forming an anti-reflection film on an insulatingfilm having a flattened surface and provided with wires arrangedthereunder; and forming a resist film and irradiating the resist filmwith light for forming a mask.
 2. A method of manufacturing asemiconductor device according to claim 1, wherein the wires are formedby burying conductive members in wiring grooves formed in a lowerinsulating film layer of the insulating film and removing the conductivemembers by means of a chemical mechanical polishing method from areasother than the wiring grooves, and the insulating film is formed withthe flattened surface on the wires by means of a deposition method.
 3. Amethod of manufacturing a semiconductor device according to claim 1,wherein the wires are formed by depositing a conductive film andpatterning the film by means of a photolithography method, and theinsulating film is formed with the flattened surface by depositing aninsulating film to cover the wires and polishing the surface of thedeposited insulating film by means of a chemical mechanical polishingmethod.
 4. A method of manufacturing a semiconductor device according toclaim 1, further comprising the step of: after said irradiating step,etching the insulating film by using the resist film as a mask to form agroove.
 5. A method of manufacturing a semiconductor device comprisingsteps of: forming a second insulating film on a first insulating film,the second insulating film having an etching rate lower than that of thefirst insulating film; forming a first resist film patterned for forminga wiring groove pattern on the second insulating film; etching thesecond insulating film in the presence of the first resist film andtransferring the wiring groove pattern into the second insulating film;forming an anti-reflection film on the second insulating film having thewiring groove pattern; forming a second resist film on theanti-reflection film; and irradiating the second resist film with light,for forming a groove pattern.
 6. A method of manufacturing asemiconductor device according to claim 5, wherein the second insulatingfilm has a film thickness small enough for a surface thereof to beregarded as flat after forming the anti-reflection film.
 7. A method ofmanufacturing a semiconductor device according to claim 5, wherein thesecond insulating film has a film thickness smaller than that of thefirst insulating film and of the second resist film.
 8. A method ofmanufacturing a semiconductor device according to claim 5, furthercomprising the steps of: after said irradiating step, etching the firstinsulating film by using the second resist film as a mask to form thegroove pattern; removing the second resist film; and etching the firstinsulating film by using the second insulating film as a mask.
 9. Amethod of manufacturing a semiconductor device according to claim 8,wherein in the first insulating film etching step, the first insulatingfilm and the second insulating film are etched by using the secondresist film as a mask.
 10. A method of manufacturing a semiconductordevice comprising steps of: forming a first mask film on a film to bepatterned and subsequently forming an anti-reflection film; forming asecond mask film on the anti-reflection film; and transferring a patterninto the film to be patterned by using the first and second mask films.11. A method of manufacturing a semiconductor device according to claim10, wherein the anti-reflection film and the first mask film are removedin a self-aligning manner relative to the second mask film.
 12. A methodof manufacturing a semiconductor device according to claim 10, whereinthe film includes a hard mask layer.
 13. A method of manufacturing asemiconductor device according to claim 10, wherein the film includes aninsulating film and a hard mask layer formed on the insulating film inthe first mask film forming step, and wherein the pattern transferringstep includes sub-steps of: (a) transferring a pattern of the first maskfilm into the hard mask layer; (b) after the step (a), removing thefirst mask film; (c) after the step (b), etching the insulating film byusing the hard mask layer as a mask.
 14. A method of manufacturing asemiconductor device according to claim 13, wherein the patterntransferring step includes the further sub-steps of etching theinsulating film by using the second mask film as a mask.
 15. A method ofmanufacturing a semiconductor device according to claim 13, wherein thefirst mask film is comprised of an insulating film.
 16. A method ofmanufacturing a semiconductor device according to claim 10, wherein thefirst mask film is comprised of a hard mask layer.
 17. A method ofmanufacturing a semiconductor device according to claim 16, wherein thefilm is comprised of an insulating film.
 18. A method of manufacturing asemiconductor device according to claim 16, wherein the patterntransferring step includes sub-steps of: (a) transferring a pattern orthe first mask film into the film; (b) after the step (a), removing thefirst mask film; and (c) after the step (b), etching the film by usingthe first mask layer as a mask.
 19. A method of manufacturing asemiconductor device according to claim 18, wherein the patterntransferring step includes the further sub-steps of etching the film byusing the second mask film as a mask.
 20. A method of manufacturing asemiconductor device according to claim 16, wherein the hard mask layerincludes metal as material.
 21. A method of manufacturing asemiconductor device according to claim 12, wherein the hard mask layerincludes metal as material.